Signal compressing apparatus

ABSTRACT

An input signal is quantized into a quantization-resultant signal. The quantization-resultant signal is compressed into a compression-resultant signal. The compression-resultant signal is formatted into a formatting-resultant signal corresponding to a predetermined format for a digital recording disc. The formatting-resultant signal includes segments corresponding to user data areas prescribed in the predetermined format. The compression-resultant signal is placed in the segments of the formatting-resultant signal. The formatting-resultant signal is encoded into an encoding-resultant signal of a CD format. The encoding-resultant signal is recorded on a recording medium.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a signal compressing apparatus such as anaudio signal compressing apparatus. Also, this invention relates to asignal recording apparatus such as an audio signal recording apparatus.Furthermore, this invention relates to a recording medium. In addition,this invention relates to an apparatus for an optical disc such as aCD-DA (Compact Disc Digital Audio), a CD-ROM (Compact Disc Read OnlyMemory), a video-CD, a DVD (Digital Video Disc), a DVD-ROM (DigitalVideo Disc Read Only Memory), a DVD-WO (Digital Video Disc Write Once),or a DVD-RAM (Digital Video Disc Random Access Memory).

2. Description of the Related Art

The CD (Compact Disc) standards prescribe that the sampling frequency fsshould be 44.1 kHz, and the quantization bit number should be 16. Thereare optical recording discs on which digital signals representing audioinformation, digital signals representing video information, or digitalsignals representing both audio information and video information arerecorded. Examples of such optical recording discs are a CD-DA (CompactDisc Digital Audio), a CD-ROM (Compact Disc Read Only Memory), avideo-CD, and a DVD (Digital Video Disc).

Audio data conforming to the CD-DA standards can not be recorded asaudio data of the CD-ROM format for the following reason. The CD-ROMformat has headers containing sync information, address information, andmode information. Accordingly, a recording capacity of a CD-ROM whichcan be used for audio information is smaller than the audio-informationrecording capacity of a CD-DA.

SUMMARY OF THE INVENTION

It is a first object of this invention to provide an improved signalcompressing apparatus.

It is a second object of this invention to provide an improved signalrecording apparatus.

It is a third object of this invention to provide an improved recordingmedium.

It is a fourth object of this invention to provide an improved apparatusfor an optical disc.

A first aspect of this invention provides a signal recording apparatuscomprising means for quantizing an input signal into aquantization-resultant signal; means for compressing thequantization-resultant signal into a compression-resultant signal; meansfor formatting the compression-resultant signal into aformatting-resultant signal corresponding to a predetermined format fora digital recording discs the formatting-resultant signal includingsegments corresponding to user data areas prescribed in thepredetermined format, the compression-resultant signal being placed inthe segments of the formatting-resultant signal; means for encoding theformatting-resultant signal into an encoding-resultant signal of a CDformat; and means for recording the encoding-resultant signal on arecording medium.

A second aspect of this invention is based on the first aspect thereof,and provides a signal recording apparatus wherein the input signalcomprises an audio signal.

A third aspect of this invention is based on the first aspect thereof,and provides a signal recording apparatus wherein the predeterminedformat for the digital recording disc is equal to a predetermined formatfor a CD-ROM.

A fourth aspect of this invention is based on the first aspect thereof,and provides a signal recording apparatus wherein the predeterminedformat for the digital recording disc is equal to a predetermined formatfor a DVD.

A fifth aspect of this invention is based on the first aspect thereof,and provides a signal recording apparatus wherein the compressing meanscomprises means for subjecting the quantization-resultant signal toorthogonal transform.

A sixth aspect of this invention is based on the fifth aspect thereof,and provides a signal recording apparatus wherein the compressing meanscomprises means for subjecting the quantization-resultant signal to aHuffman encoding process.

A seventh aspect of this invention is based on the first aspect thereof,and provides a signal recording apparatus wherein the compressing meanscomprises means for dividing the quantization-resultant signal intocomponents corresponding to divided frequency bands respectively, andmeans for compressing the components according tofrequency-band-dependent compression characteristics depending on apredetermined auditory sensation model.

An eighth aspect of this invention provides a signal compressingapparatus comprising means for quantizing an input signal into aquantization-resultant signal; means for compressing thequantization-resultant signal into a compression-resultant signal; andmeans for formatting the compression-resultant signal into aformatting-resultant signal corresponding to a predetermined format fora digital recording disc, the formatting-resultant signal includingsegments corresponding to user data areas prescribed in thepredetermined format, the compression-resultant signal being placed inthe segments of the formatting-resultant signal.

A ninth aspect of this invention is based on the eighth aspect thereof,and provides a signal compressing apparatus wherein the input signalcomprises an audio signal.

A tenth aspect of this invention is based on the eighth aspect thereof,and provides a signal compressing apparatus wherein the predeterminedformat for the digital recording disc is equal to a predetermined formatfor a CD-ROM.

An eleventh aspect of this invention is based on the eighth aspectthereof, and provides a signal compressing apparatus wherein thepredetermined format for the digital recording disc is equal to apredetermined format for a DVD.

A twelfth aspect of this invention is based on the eighth aspectthereof, and provides a signal compressing apparatus wherein thecompressing means comprises means for subjecting thequantization-resultant signal to orthogonal transform.

A thirteenth aspect of this invention is based on the twelfth aspectthereof, and provides a signal compressing apparatus wherein thecompressing means comprises means for subjecting thequantization-resultant signal to a Huffman encoding process.

A fourteenth aspect of this invention is based on the eighth aspectthereof, and provides a signal compressing apparatus wherein thecompressing means comprises means for dividing thequantization-resultant signal into components corresponding to dividedfrequency bands respectively, and means for compressing the componentsaccording to frequency-band-dependent compression characteristicsdepending on a predetermined auditory sensation model.

A fifteenth aspect of this invention provides a recording medium storingan encoding-resultant signal which is recorded on the recording mediumby the steps of quantizing an input signal into a quantization-resultantsignal; compressing the quantization-resultant signal into acompression-resultant signal; formatting the compression-resultantsignal into a formatting-resultant signal corresponding to apredetermined format for a digital recording disc, theformatting-resultant signal including segments corresponding to userdata areas prescribed in the predetermined format, thecompression-resultant signal being placed in the segments of theformatting-resultant signal; encoding the formatting-resultant signalinto an encoding-resultant signal of a CD format; and recording theencoding-resultant signal on the recording medium.

A sixteenth aspect of this invention provides an apparatus for anoptical disc, comprising a CD-DA decoder; a CD-ROM decoder; a signalexpansion decoder; means for reading out a signal from the optical disc;means for deciding which of a CD-DA, a CD-ROM, and a CD-ROM-audio theoptical disc agrees with; means for, when the optical disc agrees with aCD-DA, selecting the CD-DA decoder from among the CD-DA decoder, theCD-ROM decoder, and the signal expansion decoder and using the CD-DAdecoder to process the signal read out from the optical disc into arecovered signal; means for, when the optical disc agrees with a CD-ROM,selecting the CD-DA decoder and the CD-ROM decoder from among the CD-DAdecoder, the CD-ROM decoder, and the signal expansion decoder and usingthe CD-DA decoder and the CD-ROM decoder to process the signal read outfrom the optical disc into a recovered signal; and means for, when theoptical disc agrees with a CD-ROM-audio, using the CD-DA decoder, theCD-ROM decoder, and the signal expansion decoder to process the signalread out from the optical disc into a recovered signal.

A seventeenth aspect of this invention provides an apparatus for anoptical disc, comprising a CD-DA decoder; a CD-ROM decoder; a signalexpansion decoder; an MPEG decoder; means for reading out a signal fromthe optical disc; means for deciding which of a CD-DA, a CD-ROM-audio,and a video-CD the optical disc agrees with; means for, when the opticaldisc agrees with a CD-DA, selecting the CD-DA decoder from among theCD-DA decoder, the CD-ROM decoder, the signal expansion decoder, and theMPEG decoder and using the CD-DA decoder to process the signal read outfrom the optical disc into a recovered signal; means for, when theoptical disc agrees with a CD-ROM-audio, selecting the CD-DA decoder,the CD-ROM decoder, and the signal expansion decoder from among theCD-DA decoder, the CD-ROM decoder, the signal expansion decoder, and theMPEG decoder and using the CD-DA decoder, the CD-ROM decoder, and thesignal expansion decoder to process the signal read out from the opticaldisc into a recovered signal; and means for, when the optical discagrees with a video-CD, selecting the CD-DA decoder, the CD-ROM decoder,and the MPEG from among the CD-DA decoder, the CD-ROM decoder, thesignal expansion decoder, and the MPEG decoder and using the CD-DAdecoder, the CD-ROM decoder, and the MPEG decoder to process the signalread out from the optical disc into a recovered signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a signal compressing apparatus according toa first embodiment of this invention.

FIG. 2 is a diagram of a first format of a 1-sector-correspondingsegment of a digital signal generated by a CD-ROM encoding circuit inFIG. 1.

FIG. 3 is a diagram of a second format of a 1-sector-correspondingsegment of a digital signal generated by the CD-ROM encoding circuit inFIG. 1.

FIG. 4 is a diagram of a format of a 1-pack-corresponding segment of adigital signal generated by a DVD encoding circuit in FIG. 1.

FIG. 5 is a diagram of a drive apparatus and a CD-WO (a compact discwrite once).

FIG. 6 is a block diagram of a signal compressing apparatus according toa second embodiment of this invention.

FIG. 7 is a block diagram of a signal compressing apparatus according toa third embodiment of this invention.

FIG. 8 is a flow diagram of operation of a signal processing circuit inFIG. 7.

FIG. 9 is a flowchart of a segment of a program related to operation ofthe signal processing circuit in FIG. 7.

FIG. 10 is a frequency-domain diagram of an example of a signal power, ascale factor, a standard noise level, and an original noise level.

FIG. 11 is a block diagram of a signal compressing apparatus accordingto a fourth embodiment of this invention.

FIG. 12 is a flowchart of a first segment of a program related tooperation of a signal processing circuit in FIG. 11.

FIG. 13 is a diagram of the relation between a code amount adjustmentvalue Adj and a deviation A.

FIG. 14 is a flowchart of a second segment of the program related tooperation of the signal processing circuit in FIG. 11.

FIG. 15 is a block diagram of an apparatus for an optical disc accordingto a fifth embodiment of this invention.

FIG. 16 is a flowchart of a segment of a program related to operation ofa CPU in FIG. 15.

FIG. 17 is a block diagram of an apparatus for an optical disc accordingto a sixth embodiment of this invention.

FIG. 18 is a flowchart of a segment of a program related to operation ofa CPU in FIG. 17.

FIG. 19 is a block diagram of an apparatus for an optical disc accordingto a seventh embodiment of this invention.

FIG. 20 is a block diagram of an apparatus for an optical disc accordingto an eighth embodiment of this invention.

FIG. 21 is a block diagram of an apparatus for an optical disc accordingto a ninth embodiment of this invention.

FIG. 22 is a block diagram of an apparatus for an optical disc accordingto a tenth embodiment of this invention.

FIG. 23 is a block diagram of an apparatus for an optical disc accordingto an eleventh embodiment of this invention.

FIG. 24 is a block diagram of a compression encoder in FIG. 23.

FIG. 25 is a block diagram of an expansion decoder in FIG. 23.

FIG. 26 is a flowchart of a segment of a program related to operation ofa CPU in FIG. 23.

FIG. 27 is a block diagram of an apparatus for an optical disc accordingto a twelfth embodiment of this invention.

FIG. 28 is a flowchart of a segment of a program related to operation ofa CPU in FIG. 27.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

With reference to FIG. 1, a signal compressing apparatus has an inputterminal 1A connected to the input side of an A/D converter 1. Theoutput side of the A/D converter 1 is connected to the input side of asignal processing circuit 2.

A switch 4B has a movable contact and first and second fixed contacts.The movable contact of the switch 4B is selectively connected to eitherthe first fixed contact or the second fixed contact thereof. The movablecontact of the switch 4B is connected to the output side of the signalprocessing circuit 2. The first fixed contact of the switch 4B leads tothe input side of a CD-ROM encoding circuit 4A. The second fixed contactof the switch 4B leads to the input side of a DVD encoding circuit 6.

A switch 4C has a movable contact and first and second fixed contacts.The movable contact of the switch 4C is selectively connected to eitherthe first fixed contact or the second fixed contact thereof. The firstfixed contact of the switch 4C is connected to the output side of theCD-ROM encoding circuit 4A. The second fixed contact of the switch 4C isconnected to the output side of the DVD encoding circuit 6. The movablecontact of the switch 4C leads to an apparatus output terminal 4D. Also,the movable contact of the switch 4C leads to the input side of a CDencoding circuit (a CD-DA encoding circuit) 5. The output side of the CDencoding circuit 5 is connected to an apparatus output terminal 5A.

The switches 4B and 4C cooperate to select either the CD-ROM encodingcircuit 4A or the DVD encoding circuit 6 as an effective circuit.

A signal generator 3A outputs a clock signal having a frequency of 44.1kHz. A signal generator 3B outputs a clock signal having a frequency of48 kHz. A signal generator 3C outputs a clock signal having a frequencyof 88.2 kHz. A signal generator 3D outputs a clock signal having afrequency 96 kHz.

A switch 1B has a movable contact, and first, second, third, and fourthfixed contacts. The movable contact of the switch 1B is selectivelyconnected to one of the first, second, third, and fourth fixed contactsthereof. The movable contact of the switch 1B leads to a clock inputterminal of the A/D converter 1. The first, the second, third, andfourth fixed contacts of the switch 1B are connected to the outputterminals of the signal generators 3A, 3B, 3C, and 3D, respectively. Theswitch 1B selects one of the output signals of the signal generators 3A,3B, 3C, and 3D, and transmits the selected signal to the A/D converter 1as a sampling clock signal.

A switch 7A has a movable contact, and first, second, third, fourth,fifth, and sixth fixed contacts. The movable contact of the switch 7A isselectively connected to one of the first, second, third, fourth, fifth,and sixth fixed contacts thereof. The movable contact of the switch 7Aleads the CD-ROM encoding circuit 4A. The first second, third, fourth,fifth, and sixth fixed contacts of the switch 7A are connected to tapsor nodes in a series resistor combination 7B, respectively. The seriesresistor combination 7B is connected across a fixed-dc-voltage source7C. The switch 7A selects one of six different voltages available in theseries resistor combination 7B, and feeds the selected voltage to theCD-ROM encoding circuit 4A.

For example, the switch 7A can be operated by a user. Operation of thesignal compressing apparatus of FIG. 1 can be changed among sixdifferent modes. The six different levels of the voltage signal fed viathe switch 7A to the CD-ROM encoding circuit 4A are assigned to the sixdifferent modes of operation of the apparatus of FIG. 1, respectively.Accordingly, the switch 7A serves as a operation-mode selecting switch,and the voltage signal fed via the switch 7A to the CD-ROM encodingcircuit 4A represents an apparatus operation mode desired and selectedby the user. Thus, the voltage signal fed via the switch 7A to theCD-ROM encoding circuit 4A is also referred to as the mode signal. Aswill be made clear later, the switches 1B, 4B, and 4C are linked to theswitch 7A.

An analog audio signal is inputted to the A/D converter 1 via theapparatus input terminal 1A. The A/D converter 1 changes the inputanalog audio signal into a corresponding digital audio signal inresponse to the sampling clock signal fed via the switch 1B.Specifically, the A/D converter 1 periodically samples the input analogaudio signal at a sampling frequency decided by the frequency of thesampling clock signal. The A/D converter 1 changes or quantizes everysample of the input analog audio signal into a corresponding digitalaudio signal segment (a corresponding audio data piece) with apredetermined quantization bit number. The predetermined quantizationbit number is equal to, for example, 16 or 20. The A/D converter 1outputs the resultant digital audio signal (referred to as the firstdigital audio signal) to the signal processing circuit 2.

Generally, the input analog audio signal is composed of 2-channelsignals. The input analog audio signal may be composed of 4-channelsignals, or 6-channel signals.

The signal processing circuit 2 includes a DSP (digital signalprocessor), a microcomputer, or a similar device having a combination ofan input/output port, a processing section, a ROM, and a RAM. The signalprocessing circuit 2 operates in accordance with a program stored in theROM.

The signal processing circuit 2 is programmed to compress the firstdigital audio signal into a second digital audio signal according to apredetermined signal-compression technique including an orthogonaltransform process. The predetermined signal-compression technique mayalso include a Huffman encoding process. In this case, the orthogonaltransform process may be omitted from the predeterminedsignal-compression technique. For example, the predeterminedsignal-compression technique is selected from among knownsignal-compression techniques. The signal processing circuit 2 outputsthe second digital audio signal (the compression-resultant digital audiosignal) to the CD-ROM encoding circuit 4A or the DVD encoding circuit 6via the switch 4B.

The CD-ROM encoding circuit 4A generates auxiliary information signals(sub information signals) in response to the mode signal. The auxiliaryinformation signals includes a sync signal and a header signal.Specifically, the CD-ROM encoding circuit 4A generates at least a syncsignal and a header signal for every sector with respect to a recordingmedium (a CD-ROM). When the CD-ROM encoding circuit 4A is selected bythe switch 4B, the CD-ROM encoding circuit 4A receives the seconddigital audio signal from the signal processing circuit 2. The CD-ROMencoding circuit 4A combines the sync signal, the header signal, and thesecond digital audio signal in response to the mode signal on atime-division multiplexing basis for every sector with respect to arecording medium (a CD-ROM). The combination-resultant digital audiosignal is of a predetermined format equal to one of the CD-ROM signalformats. The combination-resultant digital audio signal is also referredto as the composite digital audio signal. During combining the signals,the CD-ROM encoding circuit 4A places the second digital audio signal ina time range corresponding to a user data area in every sector withrespect to a recording medium (a CD-ROM). When the CD-ROM encodingcircuit 44 is selected by the switch 4C, the CD-ROM encoding circuit 4Aoutputs the combination-resultant digital audio signal (the compositedigital audio signal) to the apparatus output terminal 4D and the CDencoding circuit 5.

The DVD encoding circuit 6 generates a header signal for every pack.When the DVD encoding circuit 6 is selected by the switch 4B, the DVDencoding circuit 6 receives the second digital audio signal from thesignal processing circuit 2. The DVD encoding circuit 6 combines theheader signal and the second digital audio signal on a time-divisionmultiplexing basis for every pack. The combination-resultant digitalaudio signal is of a predetermined format equal to the DVD signalformat. The combination-resultant digital audio signal is also referredto as the composite digital audio signal. During combining the signals,the DVD encoding circuit 6 places the second digital audio signal in atime range corresponding to a user data area or a packet area in everypack. When the DVD encoding circuit 6 is selected by the switch 4C, theDVD encoding circuit 6 outputs the combination-resultant digital audiosignal (the composite digital audio signal) to the apparatus outputterminal 4D and the CD encoding circuit 5.

The CD encoding circuit 5 converts the output signal of the CD-ROMencoding circuit 4A or the output signal of the DVD encoding circuit 6into a digital audio signal of a predetermined format equal to the CD-WO(compact disc write once) format or the CD-DA format. The CD encodingcircuit 5 feeds the digital audio signal of the CD-WO format or theCD-DA format to the apparatus output terminal 5A.

For example, the CD encoding circuit 5 subjects the output signal of theCD-ROM encoding circuit 4A or the output signal of the DVD encodingcircuit 6 to a CIRC (Cross Interleave Reed-Solomon Code) encodingprocess according to the CD-WO standards or the CD-DA standards. The CDencoding circuit 5 outputs the encoding-resultant digital audio signalto the apparatus output terminal 5A. Specifically, the CD encodingcircuit 5 generates an error correction signal in response to the outputsignal of the CD-ROM encoding circuit 4A or the output signal of the DVDencoding circuit 6, and adds the error correction signal to the outputsignal of the CD-ROM encoding circuit 4A or the output signal of the DVDencoding circuit 6. The error correction signal uses a cross interleaveReed-Solomon code. The CD encoding circuit 5 feeds theaddition-resultant signal to the apparatus output terminal 5A.

Operation of the signal compressing apparatus of FIG. 1 can be changedamong six different modes. During the first mode of operation, theswitch 1B selects the output signal of the signal generator 3A which hasa frequency of 44.1 kHz. The switch 1B transmits the selected signal tothe A/D converter 1 as a sampling clock signal. Accordingly, during thefirst mode of operation, the frequency of the signal sampling by the A/Dconverter 1 is equal to 44.1 kHz. During the first mode of operation,the switches 4B and 4C select the CD-ROM encoding circuit 4A. In thiscase, the CD-ROM encoding circuit 4A generates a sequence of a syncsignal, a header signal, a sub header signal, a user data block, and anEDC signal in response to the mode signal and the second digital audiosignal for every sector with respect to a recording medium (a CD-ROM).The user data block contains the second digital audio signal. During thefirst mode of operation, a 1-sector-corresponding segment of thecomposite digital audio signal generated by the CD-ROM encoding circuit4A has a form such as shown in FIG. 2. The user data block has 2,324bytes.

During the second mode of operation, the switch 1B selects the outputsignal of the signal generator 3C which has a frequency of 88.2 kHz. Theswitch 1B transmits the selected signal to the A/D converter 1 as asampling clock signal. Accordingly, during the second mode of operation,the frequency of the signal sampling by the A/D converter 1 is equal to88.2 kHz. During the second mode of operation, the switches 4B and 4Cselect the CD-ROM encoding circuit 4A. In this case, the CD-ROM encodingcircuit 4A generates a sequence of a sync signal, a header signal, a subheader signal, a user data block, and an EDC signal in response to themode signal and the second digital audio signal for every sector withrespect to a recording medium (a CD-ROM). The user data block containsthe second digital audio signal. During the second mode of operation, a1-sector-corresponding segment of the composite digital audio signalgenerated by the CD-ROM encoding circuit 4A has a form such as shown inFIG. 2. The user data block has 2,324 bytes.

During the third mode of operation, the switch 1B selects the outputsignal of the signal generator 3A which has a frequency of 44.1 kHz. Theswitch 1B transmits the selected signal to the A/D converter 1 as asampling clock signal. Accordingly, during the third mode of operation,the frequency of the signal sampling by the A/D converter 1 is equal to44.1 kHz. During the third mode of operation, the switches 4B and 4Cselect the CD-ROM encoding circuit 4A. In this case, the CD-ROM encodingcircuit 4A generates a sequence of a sync signal, a header signal, and auser data block in response to the mode signal and the second digitalaudio signal for every sector with respect to a recording medium (aCD-ROM). The user data block contains the second digital audio signal.During the third mode of operation, a 1-sector-corresponding segment ofthe composite digital audio signal generated by the CD-ROM encodingcircuit 4A has a form such as shown in FIG. 3. The user data block has2,336 bytes.

During the fourth mode of operation, the switch 1B selects the outputsignal of the signal generator 3C which has a frequency of 88.2 kHz. Theswitch 1B transmits the selected signal to the A/D converter 1 as asampling clock signal. Accordingly, during the fourth mode of operation,the frequency of the signal sampling by the A/D converter 1 is equal to88.2 kHz. During the fourth mode of operation, the switches 4B and 4Cselect the CD-ROM encoding circuit 4A. In this case, the CD-ROM encodingcircuit 4A generates a sequence of a sync signal, a header signal, and auser data block in response to the mode signal and the second digitalaudio signal for every sector with respect to a recording medium (aCD-ROM). The user data block contains the second digital audio signal.During the fourth mode of operation, a 1-sector-corresponding segment ofthe composite digital audio signal generated by the CD-ROM encodingcircuit 4A has a form such as shown in FIG. 3. The user data block has2,336 bytes.

During the fifth mode of operation, the switch 1B selects the outputsignal of the signal generator 3B which has a frequency of 48 kHz. Theswitch 1B transmits the selected signal to the A/D converter 1 as asampling clock signal. Accordingly, during the fifth mode of operation,the frequency of the signal sampling by the A/D converter 1 is equal to48 kHz. During the fifth mode of operation, the switches 4B and 4Cselect the DVD encoding circuit 6. In this case, the DVD encodingcircuit 6 generates a sequence of a header signal and a user data block(a packet or packets) in response to the second digital audio signal forevery pack. The user data block (the pack or packets) contains thesecond digital audio signal. During the fifth mode of operation, a1-pack-corresponding segment of the composite digital audio signalgenerated by the DVD encoding circuit 6 has a form such as shown in FIG.4. The user data block has 2,034 bytes.

It should be noted that in this specification, a DVD may be another discin a DVD family such as a DVD-ROM, a DVD-WO, and a DVD-RAM.

During the sixth mode of operation, the switch 1B selects the outputsignal of the signal generator 3D which has a frequency of 96 kHz. Theswitch 1B transmits the selected signal to the A/D converter 1 as asampling clock signal. Accordingly, during the sixth mode of operation,the frequency of the signal sampling by the A/D converter 1 is equal to96 kHz. During the sixth mode of operation, the switches 4B and 4Cselect the DVD encoding circuit 6. In this case, the DVD encodingcircuit 6 generates a sequence of a header signal and a user data block(a packet or packets) in response to the second digital audio signal forevery pack. The user data block (the pack or packets) contains thesecond digital audio signal. During the sixth mode of operation, a1-pack-corresponding segment of the composite digital audio signalgenerated by the DVD encoding circuit 6 has a form such as shown in FIG.4. The user data block has 2,034 bytes.

The apparatus output terminal 4D can be connected to a transmission linein, for example, a communication network. In this case, the outputsignal of the CD-ROM encoding circuit 4A or the DVD encoding circuit 6can be fed to the transmission line before being transmitted therealong.

The apparatus output terminal 4D can be connected to a pre-masteringapparatus or a mastering apparatus for a CD-ROM or a DVD. In this case,the output signal of the CD-ROM encoding circuit 4A or the DVD encodingcircuit 6 can be fed to the pre-mastering apparatus or the masteringapparatus before being recorded thereby on a pre-master disc or a masterdisc for a CD-ROM or a DVD.

The apparatus output terminal 4D can be connected to a recordingapparatus. In this case, the output signal of the CD-ROM encodingcircuit 4A or the DVD encoding circuit 6 can be fed to the recordingapparatus before being recorded thereby on a recording medium such as amagnetic tape or a magnetic disc.

FIG. 5 shows a drive apparatus 8 for a CD-WO 9. The drive apparatus 8can be connected to the output terminal 5A in FIG. 1. In this case, theoutput signal of the CD encoding circuit 5 can be fed to the driveapparatus 8 before being recorded thereby on the CD-WO 9.

Second Embodiment

FIG. 6 shows a second embodiment of this invention which is similar tothe embodiment of FIGS. 1-5 except for the following design change. Theembodiment of FIG. 6 uses a signal processing circuit 2A instead of thesignal processing circuit 2 in FIG. 1.

An analog audio signal inputted to the A/D converter 1 is composed of2-channel signals. The input analog audio signal may be composed of4-channel signals, or 6-channel signals.

The signal processing circuit 2A includes a DSP (digital signalprocessor), a microcomputer, or a similar device having a combination ofan input/output port, a processing section, a ROM, and a RAM. The signalprocessing circuit 2A operates in accordance with a program stored inthe ROM.

The signal processing circuit 2A receives the first digital audio signalfrom the A/D converter 1. The signal processing circuit 2A is programmedto process the first digital audio signal into a second digital audiosignal according to a predetermined signal-compression techniqueincluding an orthogonal transform process. The predeterminedsignal-compression technique may also include a Huffman encodingprocess. In this case, the orthogonal transform process may be omittedfrom the predetermined signal-compression technique. The signalprocessing by the signal processing circuit 2A is implemented block byblock. Here, “block” corresponds to a predetermined number “2^(m)” ofdata pieces of the first digital audio signal per channel.

Specifically, the signal processing circuit 2A subjects a set of 2^(m)data pieces of the first digital audio signal to orthogonal transform,thereby generating a signal representing the frequency spectrum of thefirst digital audio signal. The signal processing circuit 2A divides theresultant frequency-spectrum signal into signals in different frequencybands by a filtering process. The signal processing circuit 2Anormalizes and quantizes each of the frequency-band signals. The signalprocessing circuit 2A generates helper information representing theconditions of the normalization (for example, the normalization level orthe normalization bit number) and the conditions of the quantization.The signal processing circuit 2A combines thenormalization/quantization-resultant signals and the helper information.The signal processing circuit 2A subjects the combination-resultantsignal to an allocation process. The signal processing circuit 2Aoutputs the allocation-resultant signal to the switch 4B.

The signal processing circuit 2A may subject the combination-resultantsignal to a Huffman encoding process. In this case, the signalprocessing circuit 2A subjects the encoding-resultant signal to anallocation process. The signal processing circuit 2A outputs theallocation-resultant signal to the switch 4B.

Third Embodiment

FIG. 7 shows a third embodiment of this invention which is similar tothe embodiment of FIGS. 1-5 except for the following design change. Theembodiment of FIG. 7 uses a signal processing circuit 2B instead of thesignal processing circuit 2 in FIG. 1.

The signal processing circuit 2B includes a DSP (digital signalprocessor), a microcomputer, or a similar device having a combination ofan input/output port, a processing section, a ROM, and a RAM. The signalprocessing circuit 2B operates in accordance with a program stored inthe ROM.

The signal processing circuit 213 receives the first digital audiosignal from the A/D converter 1. The signal processing circuit 2B isprogrammed to process the first digital audio signal into a seconddigital audio signal according to a predetermined signal-compressiontechnique.

FIG. 8 shows a flow of operation of the signal processing circuit 2B. Itshould be noted that FIG. 8 does not show the hardware structure of thesignal processing circuit 2B. With reference to FIG. 8, a block 22subjects an input signal (that is, the first digital audio signal fromthe A/D converter 1) to a windowing process and an orthogonal transformprocess. Preferably, the orthogonal transform process is of the MDCT(modified discrete cosine transform) type. The resultant datarepresenting orthogonal transform coefficients are divided by the block22 into coefficient-representing data pieces corresponding to differentfrequency bands respectively.

A block 23 following the block 22 decides scale factors for thecoefficient-representing data pieces corresponding to the frequencybands respectively. The block 23 normalizes the coefficient-representingdata pieces in response to the decided scale factors respectively. Theblock 23 informs a block 27 of the decided scale factors.

A block 24 following the block 23 quantizes the normalization-resultantdata pieces in response to variable quantization factors (variablequantization steps). The bock 24 may implement thequantization-resultant data pieces to entropy encoding.

A block 25 following the block 23 calculates desired code amounts(desired bit numbers) from the normalization-resultant data pieces forthe frequency bands respectively. The minimum audible limitcharacteristics and the masking effects of a predetermined auditorysensation model are used in calculating the desired code amounts.

A block 26 following the block 25 calculates desired quantizationfactors (desired quantization steps) from the desired code amounts forthe frequency bands respectively. The block 26 informs the block 24 ofthe desired quantization factors (the desired quantization steps). Theblock 24 quantizes the normalization-resultant data pieces in responseto quantization factors equal to the desired quantization factors. Theblock 26 informs the block 27 of the desired quantization factors asactual quantization factors used by the block 24.

The block 27 follows the block 24. The block 27 generates helperinformation such as header information. The block 27 combines thequantization-resultant data pieces, the information of the scalefactors, the information of the quantization factors, and the helperinformation into a bit stream which is an output signal of the signalprocessing circuit 2B.

FIG. 9 is a flowchart of a segment of the program which corresponds tothe blocks 24, 25, and 26 in FIG. 8. Signal processing by the blocks 24,25, and 26 is implemented frame by frame. Here, “frame” is apredetermined time interval. As shown in FIG. 9, a first step S1 of theprogram segment decides first quantization bit numbers (firstquantization factors) for the frequency bands respectively. Regardingthe normalization-resultant data pieces, the step S1 estimates generatedbit numbers in response to the decided first quantization bit numbersfor the frequency bands respectively. The step S1 calculates a total bitnumber which equals the sum of the estimated bit numbers.

A step S2 following the step S1 calculates an available bit number inthe current frame. A step S3 following the step S2 compares thecalculated total bit number and the calculated available bit number todecide whether or not a code amount is insufficient. When the total bitnumber is greater than the available bit number, that is, when a codeamount is insufficient, the program advances from the step S3 to a stepS4. Otherwise, the program advances from the step S3 to a step S8.

The step S4 calculates band powers p[i] which are equal to the square ofthe scale factors for the frequency bands respectively. Here, “i”denotes a variable integer for identifying the frequency bands. The stepS4 calculates masking curves m[i] from the calculated band powers p[i]in accordance with the minimum audible limit characteristic and themasking effects of a predetermined auditory sensation model.Specifically, the masking curves m[i] are given by the convolution ofmodel-based reference curves r[i] and the band powers p[i].

A step S5 following the step S4 calculates standard noise levels N[i]from the minimum audible limits abs[i] and the masking curves m[i] forthe frequency bands respectively. For example, the calculation of thestandard noise levels N[i] uses an equation given as:

N[i]=max[m[i],abs[i]]

where “max” denotes an operator for selecting the greater of the valuesin the brackets.

A step S6 subsequent to the step S5 distributes deleted bits (that is,bits to be deleted) to the frequency bands according to the followingrules. First one of the deleted bits is allocated to the frequency bandhaving the highest standard noise level. Then, the standard noise levelcorresponding to this frequency band is reduced by a predeterminedlevel. Subsequently, second one of the deleted bits is allocated to thefrequency band having the highest standard noise level. Then, thestandard noise level corresponding to this frequency band is reduced bythe predetermined level. These processes are iteratively executed untila final one of the deleted bits is allocated.

In other words, first one of the deleted bits is allocated to thefrequency band having the highest standard noise level. Second one ofthe deleted bits is allocated to the frequency band having the secondhighest standard noise level. Third one of the deleted bits is allocatedto the frequency band having the third highest standard noise level.These processes are iteratively executed until a final one of thedeleted bits is allocated. During these processes, when one of thedeleted bits is allocated to a frequency band, the standard noise levelcorresponding to this frequency band is decreased by a predeterminedlevel.

Generally, the shape of the distribution of the deleted bits is similarto the shape formed by the standard noise levels N[i]. The block S6corrects the first quantization bit numbers (the first quantizationfactors) into second quantization bit numbers (second quantizationfactors) in response to the distribution of the deleted bits to thefrequency bands respectively. After the step S6, the program advances toa step S7.

The step S8 allocates surplus bits to the frequency bands. The step S8sets second quantization bit numbers (second quantization factors) equalto the first quantization bit numbers (the first quantization factors)for the frequency bands respectively. After the step S8, the programadvances to the step S7.

The step S7 quantizes the normalization-resultant data pieces inresponse to the second quantization factors (the second quantization bitnumbers) of the frequency bands respectively. After the step S7, thecurrent execution cycle of the program segment ends.

As shown in FIG. 10, the standard noise level varies frequency-band tofrequency-band even in the case where the noise level of the originalsignal is fixed independent of the frequency bands. The stepwise lineformed by the standard noise levels is shaped according to the auditorysensation model. The deleted bits are distributed to the frequency bandsaccording to the standard noise levels. Therefore, it is possible toeffectively suppress a decrease in tone quality in auditory sensationwhich would be caused by the quantization.

Fourth Embodiment

FIG. 11 shows a fourth embodiment of this invention which is similar tothe embodiment of FIGS. 7-10 except for design changes indicatedhereinafter. The embodiment of FIG. 11 uses a signal processing circuit2C instead of the signal processing circuit 2B in FIG. 7.

The signal processing circuit 2C includes a DSP (digital signalprocessor), a microcomputer, or a similar device having a combination ofan input/output port, a processing section, a ROM, and a RAM. The signalprocessing circuit 2C operates in accordance with a program stored inthe ROM.

The signal processing circuit 2C receives the first digital audio signalfrom the A/D converter 1. The signal processing circuit 2C is programmedto process the first digital audio signal into a second digital audiosignal according to a predetermined signal-compression technique.

FIG. 12 is a flowchart of a segment of the program in the signalprocessing circuit 2C. Generally, the program segment in FIG. 12 isiteratively executed. As shown in FIG. 12, a first step S11 of theprogram segment fetches information of used code amounts in all timeintervals composing an object term. For example, the object termcorresponds to the time length of a tune represented by an input audiosignal or the sum of the time lengths of all tunes for one disc. Thestep S11 calculates a mean code amount Tm among the used code amounts.The step S11 fetches information of a desired code amount Td.

A step S12 following the step S11 compares the mean code amount Tm andthe desired code amount Td to decide whether an insufficient conditionor a surplus condition occurs in code amount. When the mean code amountTm is greater than the desired code amount Td, that is, when a surpluscondition occurs, the program advances from the step S12 to a step S13.Otherwise, the program advances from the step S12 to a step S19.

The step S13 calculates the deviation (the difference) Δ which is equalto the used code amount minus the desired code amount Td for each of thetime intervals. The step S13 quantizes the deviation-Δ-representing datapiece in response to a predetermined quantization step width (apredetermined quantization step size) St for each of the time intervals.The quantization step width (the quantization step size) St is expressedin bit number. The step S13 generates a histogram related to thedeviations Δ.

A step S14 following the step S13 calculates the deviation sum Sm innegative ranges of the histogram and the deviation sum Sp in positiveranges of the histogram according to equations given as:

${Sm} = {\sum\limits_{i = \min}^{- 1}\; {{{histogram}\lbrack i\rbrack} \cdot {i} \cdot {St}}}$${Sp} = {\sum\limits_{i = 1}^{\max}{{{histogram}\lbrack i\rbrack} \cdot i \cdot {St}}}$

where “i” denotes an index of the histogram, and “min” and “max” denotean index minimum limit and an index maximum limit respectively.

A step S15 subsequent to the step S14 calculates the ratio “Sm/(Sm+Sp)”.The step S15 compares the calculated ratio with a predetermined value Bdequal to, for example, 0.33. When the calculated ratio is equal to orgreater than the predetermined value Bd, the program advances from thestep S15 to a step S16. Otherwise, the program advances from the stepS15 to a step S17.

The step S16 sets an offset value Ofs of the histogram to “0”. After thestep S16, the program advances to a step S18.

The step S17 sets the offset value Ofs so that the ratio “Sm/(Sm+Sp)”will be equal to or greater than the predetermined value Bd. After thestep S17, the program advances to the step S18.

For each of the time intervals, the step S18 compares the deviation Δwith the product of the offset value Ofs and the quantization step widthSt. When the deviation Δ is equal to or smaller than the product“Ofs·St”, the step S18 calculates a code amount adjustment value (a codeamount corrective value) Adj from the offset value Ofs and thequantization step width St according to the following equation.

Adj=−Ofs·St

When the deviation Δ is greater than the product “Ofs·St”, the step S18calculates the code amount adjustment value (the code amount correctivevalue) Adj according to the following equation.

Adj=−Ofs·St−{(Sp−Sm)/Sp}·(Δ−Ofs·St)

The step S18 calculates the code amount adjustment value (the codeamount corrective value) Adj for each of the time intervals. After thestep S18, the current execution cycle of the program segment ends.

For each of the time intervals, the step S19 calculates the code amountadjustment value (the code amount corrective value) Adj from the meancode amount Tm and the desired code amount Td according to the followingequation.

Adj=Td−Tm

After the step S19, the current execution cycle of the program segmentends.

With reference to FIG. 13, the code amount adjustment value (the codeamount corrective value) Adj varies as a function of the deviation Δ.Specifically, in a range where the deviation Δ is positive, the codeamount adjustment value (the code amount corrective value) Adj increasesas the deviation Δ increases.

FIG. 14 is a flowchart of another segment of the program in the signalprocessing circuit 2C. The program segment in FIG. 14 is executed frameby frame. As shown in FIG. 14, a first step S21 of the program segmentdecides first quantization bit numbers (first quantization factors) forthe frequency bands respectively. Regarding the normalization-resultantdata pieces, the step S21 estimates generated bit numbers in response tothe decided first quantization bit numbers for the frequency bandsrespectively. The step S21 calculates a total bit number which equalsthe sum of the estimated bit numbers.

A step S22 following the step S21 fetches information of the code amountadjustment value (the code amount corrective value) Adj for the currentframe.

A step S23 subsequent to the step S22 decides whether or not the codeamount adjustment value (the code amount corrective value) Adj isnegative. When the code amount adjustment value (the code amountcorrective value) Adj is negative, the program advances from the stepS23 to a step S24. Otherwise, the program advances from the step S23 toa step S28.

The step S24 calculates band powers p[i] which are equal to the squareof the scale factors for the frequency bands respectively. Here, “i”denotes a variable integer for identifying the frequency bands. The stepS24 calculates masking curves m[i] from the calculated band powers p[i]in accordance with the minimum audible limit characteristic and themasking effects of a predetermined auditory sensation model.Specifically, the masking curves m[i] are given by the convolution ofmodel-based reference curves r[i] and the band powers p[i].

A step S25 following the step S24 calculates standard noise levels N[i]from the minimum audible limits abs[i] and the masking curves m[i] forthe frequency bands respectively. For example, the calculation of thestandard noise levels N[i] uses an equation given as:

N[i]=max[m[i],abs[i]]

where “max” denotes an operator for selecting the greater of the valuesin the brackets.

A step S26 subsequent to the step S25 distributes deleted bits (that is,bits to be deleted) to the frequency bands according to the followingrules. First one of the deleted bits is allocated to the frequency bandhaving the highest standard noise level. Then, the standard noise levelcorresponding to this frequency band is reduced by a predeterminedlevel. Subsequently, second one of the deleted bits is allocated to thefrequency band having the highest standard noise level. Then, thestandard noise level corresponding to this frequency band is reduced bythe predetermined level. These processes are iteratively executed untila final one of the deleted bits is allocated.

In other words, first one of the deleted bits is allocated to thefrequency band having the highest standard noise level. Second one ofthe deleted bits is allocated to the frequency band having the secondhighest standard noise level. Third one of the deleted bits is allocatedto the frequency band having the third highest standard noise level.These processes are iteratively executed until a final one of thedeleted bits is allocated. During these processes, when one of thedeleted bits is allocated to a frequency band, the standard noise levelcorresponding to this frequency band is decreased by a predeterminedlevel.

Generally, the shape of the distribution of the deleted bits is similarto the shape formed by the standard noise levels N[i]. The block S26corrects the first quantization bit numbers (the first quantizationfactors) into second quantization bit numbers (second quantizationfactors) in response to the distribution of the deleted bits to thefrequency bands respectively. After the step S26, the program advancesto a step S27.

The step S28 allocates surplus bits to the frequency bands. The step S28sets second quantization bit numbers (second quantization factors) equalto the first quantization bit numbers (the first quantization factors)for the frequency bands respectively. After the step S28, the programadvances to the step S27.

The step S27 quantizes the normalization-resultant data pieces inresponse to the second quantization factors (the second quantization bitnumbers) of the frequency bands respectively. After the step S27, thecurrent execution cycle of the program segment ends.

Fifth Embodiment

FIG. 15 shows an apparatus for an optical disc 101 which can be selectedfrom among various discs such as a CD-DA, a CD-ROM, and a CD-ROM-audio.The apparatus of FIG. 15 includes a spindle motor 102, an optical head103, a spindle motor servo section 104, a focusing tracking servosection 105, and a servo control circuit 106. The spindle motor servosection 104 is connected between the spindle motor 102 and the servocontrol circuit 106. The focusing tracking servo section 105 isconnected between the optical head 103 and the servo control circuit106.

The optical disc 101 can be placed into and out of a normal positionwithin the apparatus of FIG. 15. The spindle motor 102 serves to rotatethe optical disc 101 placed in the normal position. The spindle motorservo section 104 controls the spindle motor 104 in response to anoutput signal of the servo control circuit 106 to implement control ofthe rotational speed of the optical disc 101. The focusing trackingservo section 105 controls the optical head 103 in response to outputsignals of the servo control circuit 106 to implement focusing controlof the optical head 103 and tracking control of the optical head 103.

The optical head 103 is electrically connected to an RF amplifier 107followed by a reproducing decoder 108. During a playback mode ofoperation of the apparatus of FIG. 15, the optical head 103 reads outinformation from the optical disc 101, and outputs an RF signalrepresenting the read-out information. The output signal of the opticalhead 103 is amplified by the RF amplifier 107. Theamplification-resultant signal is outputted from the RF amplifier 107 tothe reproducing decoder 108. The reproducing decoder 108 subjects theoutput signal of the RF amplifier 107 to EFM demodulation, therebyrecovering data corresponding to the information recorded on the opticaldisc 101.

The optical head 103 is electrically connected to a laser drive section109 following a recording encoder 110. During a recording mode ofoperation of the apparatus of FIG. 15, the recording encoder 110subjects recorded data (data to be recorded) to EFM modulation. Therecording encoder 110 outputs the modulation-resultant signal to thelaser drive section 109. The optical head 103 generates a laser lightbeam. The optical head 103 applies the laser light beam to the opticaldisc 101. The laser drive section 109 controls the power or theintensity of the laser light beam in response to the output signal ofthe recording encoder 110 so that information corresponding to therecorded data can be recorded on the optical disc 101.

The servo control circuit 106 is connected to the reproducing decoder108, the recording encoder 110, and a CPU 117. The servo control circuit106 adjusts the spindle motor servo section 104 and the focusingtracking servo section 105 in response to output signals of thereproducing decoder 108, the recording encoder 110, and the CPU 117.

A signal processing circuit 111 is connected to the reproducing decoder108 and the recording encoder 110. The signal processing circuit 111 isconnected to apparatus output terminals 112A and 112B via an outputcircuit 112. An apparatus input terminal 113A is connected to the signalprocessing circuit 111 via an input circuit 113.

During the playback mode of operation of the apparatus of FIG. 15, thereproducing decoder 108 outputs the recovered data to the signalprocessing circuit 111. The signal processing circuit 111 processes therecovered data. The signal processing circuit 111 outputs theprocessing-resultant data to the output circuit 112. The output circuit112 has a section which separates the processing-resultant data intoaudio data and video data. The output circuit 112 has a first D/Aconverter which changes the audio data into a corresponding analog audiosignal. The output circuit 112 feeds the analog audio signal to theapparatus output terminal 112A. The output circuit 112 has a second D/Aconverter which changes the video data into a corresponding analog videosignal. The output circuit 112 feeds the analog video signal to theapparatus output terminal 112B.

During the recording mode of operation of the apparatus of FIG. 15, aninput analog audio signal to be recorded travels to the input circuit113 via the apparatus input terminal 113A. The input circuit 113 has anA/D converter which changes the input analog audio signal into acorresponding digital audio signal. The input circuit 113 feeds thedigital audio signal to the signal processing circuit 111. The signalprocessing circuit 111 processes the digital audio signal into recordeddata (data to be recorded). The signal processing circuit 111 outputsthe recorded data to the recording encoder 110.

As previously explained, the CPU 117 is connected to the servo controlcircuit 106. The CPU 117 is also connected to a CPU 114, an operationunit 115, and a display unit 116. Operation of the apparatus of FIG. 15is changeable among different modes including the playback mode and therecording mode. The operation unit 115 has keys for selecting anddesignating one out of the different modes of operation of the apparatusof FIG. 15. The keys in the operation unit 115 can be operated by auser. The operation unit 115 informs the CPU 117 of the currentlydesignated operation mode.

The operation unit 115 has a button for selecting and designating oneout of different formats. The button in the operation unit 115 can beoperated by the user. The operation unit 115 informs the CPU 117 of thecurrently designated format.

The CPU 117 has a combination of an input/output port, a processingsection, a ROM, and a RAM. The CPU 117 operates in accordance with aprogram stored in the ROM. The CPU 117 is programmed to implement thefollowing processes. The CPU 117 transfers the information of thecurrently designated operation mode and the information of the currentlydesignated format to the CPU 114. The CPU 117 communicates with theservo control circuit 106. The CPU 117 communicates with the CPU 114.The CPU 117 generates a display signal in response to the informationfrom the operation unit 115, information from the servo control circuit106, and information from the CPU 114. The CPU 117 outputs the displaysignal to the display unit 116. The display signal is indicated by thedisplay unit 116.

As previously indicated, the CPU 114 is connected to the CPU 117. TheCPU 114 is also connected to the signal processing circuit 111. The CPU114 has a combination of an input/output port, a processing section, aROM, and a RAM. The CPU 114 operates in accordance with a program storedin the ROM. The CPU 114 is programmed to control the signal processingcircuit 111 in response to information from the CPU 117.

The signal processing circuit 111 includes a CD-DA encoder 120A a CD-DAdecoder 120B, a CD-ROM encoder 121, a CD-ROM decoder 122, switches 123and 124, an orthogonal transform/Huffman encoder 125, an orthogonaltransform/Huffman decoder 126, and switches 127 and 128.

The input side of the CD-DA decoder 120B is connected to the output sideof the reproducing decoder 108. The output side of the CD-DA decoder120B is connected to the input side of the CD-ROM decoder 122. Theoutput side of the CD-DA decoder 120B is also connected to the CPU 114.The switch 124 has a movable contact and fixed contacts “a” and “b”. Theswitch 124 has a control terminal. The switch 124 is changeable amongthree different states in response to a signal fed to the controlterminal. When the switch 124 assumes a first state, the movable contactthereof connects with the fixed contact “a” thereof and disconnects fromthe fixed contact “b” thereof. When the switch 124 assumes a secondstate, the movable contact thereof connects with the fixed contact “b”thereof and disconnects from the fixed contact “a” thereof. When theswitch 124 assumes a third state, the movable contact thereof connectswith neither the fixed contact “a” thereof nor the fixed contact “b”thereof. The control terminal of the switch 124 is connected to the CPU114. The fixed contact “a” of the switch 124 leads from the output sideof the CD-ROM decoder 122. The fixed contact “b” of the switch 124 leadsfrom the output side of the CD-DA decoder 120B. The movable contact ofthe switch 124 leads to the input side of the orthogonaltransform/Huffman decoder 126.

The switch 128 has a movable contact and fixed contacts “c” and “d”. Theswitch 128 has a control terminal. The switch 128 is changeable amongthree different states in response to a signal fed to the controlterminal. When the switch 128 assumes a first state, the movable contactthereof connects with the filed contact “c” thereof and disconnects fromthe fixed contact “d” thereof. When the switch 128 assumes a secondstate, the movable contact thereof connects with the fixed contact “d”thereof and disconnects from the fixed contact “c” thereof. When theswitch 128 assumes a third state, the movable contact thereof connectswith neither the fixed contact “c” thereof nor the fixed contact “d”thereof. The control terminal of the switch 128 is connected to the CPU114. The fixed contact “c” of the switch 128 leads from the output sideof the orthogonal transform/Huffman decoder 126. The fixed contact “d”of the switch 128 leads from the movable contact of the switch 124. Themovable contact of the switch 128 leads to the input side of the outputcircuit 112. The output side of the orthogonal transform/Huffman decoder126 is connected to the CPU 114.

The switch 127 has a movable contact and fixed contacts “g” and “h”. Theswitch 127 has a control terminal. The switch 127 is changeable amongthree different states in response to a signal fed to the controlterminal. When the switch 127 assumes a first state, the movable contactthereof connects with the fixed contact “g” thereof and disconnects fromthe fixed contact “h” thereof. When the switch 127 assumes a secondstate, the movable contact thereof connects with the fixed contact “h”thereof and disconnects from the fixed contact “g” thereof. When theswitch 127 assumes a third state, the movable contact thereof connectswith neither the fixed contact “g” thereof nor the fixed contact “h”thereof. The control terminal of the switch 127 is connected to the CPU114. The movable contact of the switch 127 leads from the output side ofthe input circuit 113. The fixed contact “h” of the switch 127 leads tothe input side of the orthogonal transform/Huffman encoder 125.

The switch 123 has a movable contact and fixed contacts “e” and “f”. Theswitch 123 has a control terminal. The switch 123 is changeable amongthree different states in response to a signal fed to the controlterminal. When the switch 123 assumes a first state, the movable contactthereof connects with the fixed contact “e” thereof and disconnects fromthe fixed contact “f” thereof. When the switch 123 assumes a secondstate, the movable contact thereof connects with the fixed contact “f”thereof and disconnects from the fixed contact “e” thereof. When theswitch 123 assumes a third state, the movable contact thereof connectswith neither the fixed contact “e” thereof nor the fixed contact “f”thereof. The control terminal of the switch 123 is connected to the CPU114. The movable contact of the switch 123 leads from the fixed contact“g” of the switch 127 and the output side of the orthogonaltransform/Huffman encoder 125. The fixed contact “e” of the switch 123leads to the input side of the CD-DA encoder 120A. The fixed contact “f”of the switch 123 leads to the input side of the CD-ROM encoder 121. Theoutput side of the CD-ROM encoder 121 is connected to the input side ofthe CD-DA encoder 120A. The output side of the CD-DA encoder 120A isconnected to the input side of the recording encoder 110.

The CPU 114 is programmed to control the switches 123, 124, 127, and 128in the signal processing circuit 111 as follows. It is assumed that theuser designates the recording mode of operation of the apparatus of FIG.15 by actuating the operation unit 115. In this case, the user alsodesignates the format by actuating the operation unit 115. Generally,the designated format corresponds to the standards of an optical disc101 set in the normal position within the apparatus of FIG. 15. Theoperation unit 115 informs the CPU 117 that the recording mode ofoperation is currently designated. Also, the operation unit 115 informsthe CPU 117 of the currently designated format. The CPU 117 transfersthe information of the currently designated operation mode and thecurrently designated format to the CPU 114. When the CPU 114 is informedthat the recording mode of operation is currently designated, the CPU114 sets the switches 124 and 128 in their third states. In this case,the movable contact of the switch 124 separates from both the fixedcontacts “a” and “b” thereof while the movable contact of the switch 128separates from both the fixed contacts “c” and “d” thereof. Therefore,none of the orthogonal transform/Huffman decoder 126, the CD-ROM decoder122, and the CD-DA decoder 120B is connected to the output circuit 112.The CPU 114 recognizes the currently designated format. When thecurrently designated format agrees with the CD-DA format, the CPU 114controls the switches 123 and 127 so that the movable contact of theswitch 123 connects with the fixed contact “e” thereof and the movablecontact of the switch 127 connects with the fixed contact “g” thereof.Therefore, the CD-DA encoder 120A is connected to the input circuit 113while the CD-ROM encoder 121 and the orthogonal transform/Huffmanencoder 125 are disconnected from the input circuit 113. When thecurrently designated format agrees with the CD-ROM format, the CPU 114controls the switches 123 and 127 so that the movable contact of theswitch 123 connects with the fixed contact “f” thereof and the movablecontact of the switch 127 connects with the fixed contact “g” thereof.Therefore, the CD-ROM encoder 121 is connected to the input circuit 113while the orthogonal transform/Huffman encoder 125 is disconnected fromthe input circuit 113. When the currently designated format agrees withthe CD-ROM-audio format, the CPU 114 controls the switches 123 and 127so that the movable contact of the switch 123 connects with the fixedcontact “f” thereof and the movable contact of the switch 127 connectswith the fixed contact “h” thereof. Therefore, the orthogonaltransform/Huffman encoder 125 is connected to the input circuit 113while the CD-ROM encoder 121 is connected to the orthogonaltransform/Huffman encoder 125.

During the recording mode of operation of the apparatus of FIG. 15, theservo control circuit 106 adjusts the spindle servo section 104 tooptimize the rotational speed of the spindle motor 102, that is, therotational speed of the optical disc 101. In addition, the servo controlcircuit 106 adjusts the focusing tracking servo section 105 to optimizefocusing and tracking conditions of the optical head 103 relative to theoptical disc 101. At a start of the recording mode of operation of theapparatus of FIG. 15, the CPU 117 informs the servo control circuit 106of a desired initial position of the optical head 103 relative to theoptical head 101. The servo control circuit 106 adjusts the focusingtracking servo section 105 in response to the positional informationfrom the CPU 117, thereby setting the optical head 103 in a positionequal to the desired initial position. During the recording mode ofoperation of the apparatus of FIG. 15, the servo control circuit 106adjusts the focusing tracking servo section 105 to move the optical head103 from the initial position to scan the optical disc 101.

During the recording mode of operation of the apparatus of FIG. 15, aninput analog audio signal to be recorded travels to the input circuit113 via the apparatus input terminal 113A. The input circuit 113 changesthe input analog audio signal into a corresponding digital audio signal.In the case where the currently designated format agrees with the CD-DAformat, the digital audio signal is transmitted from the input circuit113 to the CD-DA encoder 120A. The CD-DA encoder 120A subjects thedigital audio signal to a CIRC (Cross Interleave Reed-Solomon Code)encoding process according to the CD-DA standards. The CD-DA encoder120A outputs the encoding-resultant digital audio signal to therecording encoder 110 as recorded data (data to be recorded) of theCD-DA format. Specifically, the CD-DA encoder 120A generates an errorcorrection signal in response to the digital audio signal, and adds theerror correction signal to the digital audio signal. The errorcorrection signal uses a cross interleave Reed-Solomon code. The CD-DAencoder 120A outputs the addition-resultant signal to the recordingencoder 110. The recording encoder 110 subjects the recorded data of theCD-DA format to the EFM modulation. The recording encoder 110 outputsthe modulation-resultant signal to the laser drive section 109. Theoptical bead 103 generates a laser light beam. The optical head 103applies the laser light beam to the optical disc 101. The laser drivesection 109 controls the power or the intensity of the laser light beamin response to the output signal of the recording encoder 110 so thatinformation corresponding to the recorded data of the CD-DA format isrecorded on the optical disc 101. Furthermore, TOC information relatedto the recorded data is generated, and the TOC information is recordedon an inner area of the optical disc 101.

During the recording mode of operation of the apparatus of FIG. 15, whenthe currently designated format agrees with the CD-ROM format, thedigital audio signal is transmitted from the input circuit 113 to theCD-ROM encoder 121. The CD-ROM encoder 121 subjects the digital audiosignal to a CD-ROM encoding process including an interleaving processaccording to the CD-ROM (XA) standards. The CD-ROM encoder 121 outputsthe process-resultant digital audio signal to the CD-DA encoder 120A.The CD-DA encoder 120A subjects the output signal of the CD-ROM encoder121 to the CIRC encoding process. The CD-DA encoder 120A outputs theencoding-resultant digital audio signal to the recording encoder 110 asrecorded data (data to be recorded) of the CD-ROM format. The recordingencoder 110 subjects the recorded data of the CD-ROM format to the EFMmodulation. The recording encoder 110 outputs the modulation-resultantsignal to the laser drive section 109. The optical head 103 applies thelaser light beam to the optical disc 101. The laser drive section 109controls the power or the intensity of the laser light beam in responseto the output signal of the recording encoder 110 so that informationcorresponding to the recorded data of the CD-ROM format is recorded onthe optical disc 101. Furthermore, TOC information related to therecorded data is generated, and the TOC information is recorded on theinner area of the optical disc 101.

During the recording mode of operation of the apparatus of FIG. 15, whenthe currently designated format agrees with the CD-ROM-audio format, thedigital audio signal is transmitted from the input circuit 113 to theorthogonal transform/Huffman encoder 125. The orthogonaltransform/Huffman encoder 125 subjects the digital audio signal toorthogonal transform and a Huffman encoding process to compress thedigital audio signal. The orthogonal transform/Huffman encoder 125outputs the resultant digital audio signal to the CD-ROM encoder 121.The CD-ROM encoder 121 subjects the output signal of the orthogonaltransform/Huffman encoder 125 to the CD-ROM encoding process includingthe interleaving process. The CD-ROM encoder 121 outputs theprocess-resultant digital audio signal to the CD-DA encoder 120A. TheCD-DA encoder 120A subjects the output signal of the CD-ROM encoder 121to the CIRC encoding process. The CD-DA encoder 120A outputs theencoding-resultant digital audio signal to the recording encoder 110 asrecorded data (data to be recorded) of the CD-ROM-audio format. Therecording encoder 110 subjects the recorded data of the CD-ROM-audioformat to the EFM modulation. The recording encoder 110 outputs themodulation-resultant signal to the laser drive section 109. The opticalhead 103 applies the laser light beam to the optical disc 101. The laserdrive section 109 controls the power or the intensity of the laser lightbeam in response to the output signal of the recording encoder 110 sothat information corresponding to the recorded data of the CD-ROM-audioformat is recorded on the optical disc 101. Furthermore, TOC informationrelated to the recorded data is generated, and the TOC information isrecorded on the inner area of the optical disc 101.

It is assumed that the user places an optical disc 101 in the normalposition within the apparatus of FIG. 15, and then designates theplayback mode of operation of the apparatus of FIG. 15 by actuating theoperation unit 115. The operation control unit 115 informs the CPU 117that the playback mode of operation is currently designated. In thiscase, the CPU 117 starts the apparatus of FIG. 15 to operate in theplayback mode. During the playback mode of operation of the apparatus ofFIG. 15, the servo control circuit 106 adjusts the spindle servo section104 to optimize the rotational speed of the spindle motor 102, that is,the rotational speed of the optical disc 101. In addition, the servocontrol circuit 106 adjusts the focusing tracking servo section 105 tooptimize focusing and tracking conditions of the optical head 103relative to the optical disc 101. On the other hand, the optical head103 reads out information from the optical disc 101, and outputs an RFsignal representing the read-out information. The output signal of theoptical head 103 is amplified by the RF amplifier 107. Theamplification-resultant signal is outputted from the RF amplifier 107 tothe reproducing decoder 108. The reproducing decoder 108 subjects theoutput signal of the RF amplifier 107 to the EFM demodulation, therebyrecovering data corresponding to the information recorded on the opticaldisc 101. The reproducing decoder 108 outputs the recovered data to theCD-DA decoder 120B. The CO-DA decoder 120B subjects the output signal ofthe reproducing decoder 108 to a CIRC decoding process (an errorcorrection process). The CD-DA decoder 120B outputs thedecoding-resultant signal to the CPU 114 and the CD-ROM decoder 122.

At a start of the playback mode of operation of the apparatus of FIG.15, the CPU 117 informs the servo control circuit 106 of a desiredinitial position of the optical head 103 relative to the optical head101. The servo control circuit 106 adjusts the focusing tracking servosection 105 in response to the positional information from the CPU 117,thereby setting the optical head 103 in a position equal to the desiredinitial position. In this case, the desired initial position correspondsto a starting end of an inner area of the optical disc 101. During thestart of the recording mode of operation of the apparatus of FIG. 15,the servo control circuit 106 adjusts the focusing tracking servosection 105 to move the optical head 103 from the initial position toread out TOC information from the inner area of the optical disc 101.The CD-DA decoder 120B outputs reproduced TOC information to the CPU114. The CPU 114 transfers the TOC information to the RAM within the CPU117.

Generally, TOC information contains four control bits Q1, Q2, Q3, andQ4. Among them, the control bit Q2 is used as an indication of the typeof a related optical disc 101. Specifically, the control bit Q2 being“0” indicates that the related optical disc 101 agrees with a CD-DA. Thecontrol bit Q2 being “1” indicates that the related optical disc 101agrees with a CD-ROM or a CD-ROM-audio.

It should be noted that some of CD-ROM's are devoid of TOC information.Also, some of CD-ROM-audios are devoid of TOC information.

FIG. 16 is a flowchart of a segment of the program in the CPU 114. Theprogram segment in FIG. 16 relates to the playback mode of operation ofthe apparatus of FIG. 15. As shown in FIG. 16, a first step S101 of theprogram segment reads out TOC information from the RAM within the CPU117.

A step S102 following the step S101 decides whether or not the TOCinformation is present, that is, whether or not the TOC information hasbeen successfully read out from the optical disc 101. When the TOCinformation is present, that is, when the TOC information has beensuccessfully read out from the optical disc 101, the program advancesfrom the step S102 to a step S103. Otherwise, the program advances fromthe step S102 to a step S107.

The step S103 decides whether or not the control bit Q2 in the TOCinformation is “1”. When the control bit Q2 is “1”, the program advancesfrom the step S103 to the step S107. When the control bit Q2 is “0”, theprogram advances from the step S103 to a step S105. In this case, it isdecided that the optical disc 101 agrees with a CD-DA.

Data recorded on a CD-ROM or a CD-ROM-audio has a sync signal of a firsttype. Data recorded on a CD-DA has a sync signal of a second typedifferent from the first type. The step S103 may decide whether or not async signal of the first type is present in reproduced data. In thiscase, when a sync signal of the first type is not present, it is decidedthat the optical disc 101 agrees with a CD-DA.

The step S105 controls the switches 124 and 128 so that the movablecontact of the switch 124 will connect with the fixed contact “b”thereof while the movable contact of the switch 128 will connect withthe fixed contact “d” thereof. In this case, the CD-DA decoder 120B isconnected to the output circuit 112 while the CD-ROM decoder 122 and theorthogonal transform/Huffman decoder 126 are disconnected from theoutput circuit 112.

A step S106 following the step S105 controls the CPU 117 so thatinformation will be reproduced from first and later tracks on theoptical disc 101. In this case, the CD-DA decoder 120B outputsreproduced data to the output circuit 112. After the step S106, thecurrent execution cycle of the program segment ends.

The step S107 controls the CPU 117 so that information will bereproduced from the first track on the optical disc 101. The step S107receives reproduced data from the CD-DA decoder 120B which representsthe first-track information.

When the optical disc 101 agrees with a CD-ROM-audio, the first-trackinformation has CD-ROM-audio code words rather than CD-ROM code words.When the optical disc 101 agrees with a CD-ROM, the first-trackinformation has CD-ROM code words rather than CD-ROM-audio code words.

A step S108 subsequent to the step S107 decides whether or not thefirst-track information has CD-ROM-audio code words. When thefirst-track information has CD-ROM-audio code words, the programadvances from the step S108 to a step S109. In this case, it is decidedthat the optical disc 101 agrees with a CD-ROM-audio. When thefirst-track information does not have any CD-ROM-audio code words, theprogram advances from the step S108 to a step S117.

The step S109 controls the switch 124 so that the movable contact of theswitch 124 will connect with the fixed contact “a” thereof. In thiscase, the orthogonal transform/Huffman decoder 126 is connected to theCD-ROM decoder 122.

A step S111 following the step S109 controls the CPU 117 so that checkdata will be read out from a given track on the optical disc 101. Inthis case, the CD-DA decoder 120B outputs reproduced check data to theCD-ROM decoder 122. The CD-ROM decoder 122 subjects the reproduced checkdata to a CD-ROM decoding process including a de-interleaving process(an inverse interleaving process). The CD-ROM decoder 122 outputs theprocess-resultant data to the orthogonal transform/Huffman decoder 126.The orthogonal transform/Huffman decoder 126 subjects the output signalof the CD-ROM decoder 122 to inverse orthogonal transform and a Huffmandecoding process. The orthogonal transform/Huffman decoder 126 outputsthe resultant data to the CPU 114 as decoding-resultant datacorresponding to the reproduced check data. The step S111 receives thedecoding-resultant data from the orthogonal transform/Huffman decoder126 which corresponds to the reproduced check data.

A step S113 subsequent to the step S111 decides whether or not thedecoding-resultant data corresponding to the reproduced check data isnormal. When the decoding-resultant data is normal, the program advancesfrom the step S113 to a step S115. Otherwise, the program advances fromthe step S113 to a step S126.

The step S115 controls the switch 128 so that the movable contact of theswitch 128 will connect with the fixed contact “c” thereof. In thiscase, the orthogonal transform/Huffman decoder 126 is connected to theoutput circuit 112.

A step S116 following the step S115 controls the CPU 117 so thatinformation will be reproduced from second and later tracks on theoptical disc 101. In this case, the CD-DA decoder 120B outputsreproduced data to the CD-ROM decoder 122. The CD-ROM decoder 122subjects the reproduced data to the CD-ROM decoding process includingthe de-interleaving process. The CD-ROM decoder 122 outputs theprocess-resultant data to the orthogonal transform/Huffman decoder 126.The orthogonal transform/Huffman decoder 126 subjects the output signalof the CD-ROM decoder 122 to the inverse orthogonal transform and theHuffman decoding process. The orthogonal transform/Huffman decoder 126outputs the resultant data to the output circuit 112. After the stepS116, the current execution cycle of the program segment ends.

The step S117 decides whether or not the first-track information hasCD-ROM code words. When the first-track information has CD-ROM codewords, the program advances from the step S117 to a step S118. In thiscase, it is decided that the optical disc 101 agrees with a CD-ROM. Whenthe first-track information does not have any CD-ROM code words, theprogram advances from the step S117 to the step S126.

The step S118 controls the switches 124 and 128 so that the movablecontact of the switch 124 will connect with the fixed contact “a”thereof while the movable contact of the switch 128 will connect withthe fixed contact “d” thereof. In this case, the CD-ROM decoder 122 isconnected to the output circuit 112 while the CD-DA decoder 120B and theorthogonal transform/Huffman decoder 126 are disconnected from theoutput circuit 112.

A step S125 following the step S118 controls the CPU 117 so thatinformation will be reproduced from the first and later tracks on theoptical disc 101. In this case, the CD-DA decoder 120B outputsreproduced data to the CD-ROM decoder 122. The CD-ROM decoder 122subjects the reproduced data to the CD-ROM decoding process includingthe de-interleaving process. The CD-ROM decoder 122 outputs theprocess-resultant data to the output circuit 112. After the step S125,the current execution cycle of the program segment ends.

The step S126 controls the CPU 117 so that the CPU 117 will output agiven display signal to the display unit 116. The given display signalis indicated by the display unit 116. The given display signalrepresents that information can not be normally reproduced from theoptical disc 101. In other words, the given display signal represents afailure of the reproduction of information from the optical disc 101.After the step S126, the current execution cycle of the program segmentends.

It should be noted that the CD-ROM encoder 121 and the CD-ROM decoder122 may be replaced by a DVD encoder (a DVD packing encoder) and a DVDdecoder (a DVD unpacking decoder), respectively. In this case, the stepS117 in FIG. 16 is modified to refer to MPEG code words rather thanCD-ROM code words.

Sixth Embodiment

FIG. 17 shows a sixth embodiment of this invention which is similar tothe embodiment of FIG. 15 except for the following design changes. Theembodiment of FIG. 17 includes a CPU 114A instead of the CPU 114 in FIG.15. The embodiment of FIG. 17 includes a switch 128A instead of theswitch 128 in FIG. 15. The embodiment of FIG. 17 includes an MPEGdecoder 129. The embodiment of FIG. 17 includes an input circuit 113Binstead of the input circuit 113 in FIG. 15. The embodiment of FIG. 17is able to handle an optical disc 101 which can be selected from amongvarious discs such as a CD-DA, a CD-ROM-audio, and a video-CD.

A first input side of the input circuit 113B is connected to anapparatus input terminal 113C. A second input side of the input circuit113B is connected to an apparatus input terminal 113D. The output sideof the input circuit 113B is connected to the movable contact of theswitch 127.

During the recording mode of operation of the apparatus of FIG. 17 for avideo-CD, an input analog audio signal is fed to the input circuit 113Bvia the apparatus input terminal 113C. In addition, an input analogvideo signal is fed to the input circuit 113B via the apparatus inputterminal 113D. The input circuit 113B has a first A/D converter whichchanges the input analog audio signal into a corresponding digital audiosignal. The input circuit 113B has a second A/D converter which changesthe input analog video signal into a corresponding digital video signal.The input circuit 113B has a section which combines the digital audiosignal and the digital video signal into a composite digital signal. Theinput circuit 113B outputs the composite digital signal to the movablecontact of the switch 127. The CPU 114 controls the switches 123 and 127so that the output signal of the input circuit 113B will bypass theorthogonal transform/Huffman encoder 125 and will travel to the CD-ROMencoder 121.

The switch 128A has a movable contact and fixed contacts “c”, “d”, and“j”. The switch 128A has a control terminal. The switch 128A ischangeable among four different states in response to a signal fed tothe control terminal. When the switch 128A assumes a first state, themovable contact thereof connects with the fixed contact “c” thereof anddisconnects from the fixed contact “d” and “j” thereof. When the switch128A assumes a second state, the movable contact thereof connects withthe fixed contact “d” thereof and disconnects from the fixed contacts“c” and “j” thereof. When the switch 128A assumes a third state, themovable contact thereof connects with the fixed contact “j” thereof anddisconnects from the fixed contacts “c” and “d” thereof. When the switch128A assumes a fourth state, the movable contact thereof connects withnone of the fixed contacts “c”, “d”, and “j” thereof. The controlterminal of the switch 128A is connected to the CPU 114A. The fixedcontact “c” of the switch 128A leads from the output side of theorthogonal transform/Huffman decoder 126. The fixed contact “d” of theswitch 128A leads from the movable contact of the switch 124. The fixedcontact “j” of the switch 128A leads from the output side of the MPEGdecoder 129. The movable contact of the switch 128A leads to the inputside of the output circuit 112. The input side of the MPEG decoder 129leads from the movable contact of the switch 124. The output side of theMPEG decoder 129 is connected to the CPU 114A.

FIG. 18 is a flowchart of a segment of a program in the CPU 114A. Theprogram segment in FIG. 18 is similar to the program segment in FIG. 16except for the following design changes. With reference to FIG. 18, astep S117A which replaces the step S117 in FIG. 16 decides whether ornot the first-track information has video-CD code words. When thefirst-track information has video-CD code words, the program advancesfrom the step S117A to a step S118A. In this case, it is decided thatthe optical disc 101 agrees with a video-CD. When the first-trackinformation does not have any video-CD code words, the program advancesfrom the step S117A to the step S126.

The step S118A controls the switch 124 so that the movable contact ofthe switch 124 will connect with the fixed contact “a” thereof. In thiscase, the MPEG decoder 129 is connected to the CD-ROM decoder 122.

A step S120A following the step S118A controls the CPU 117 so thatinformation will be read out from a second track on the optical disc101. In this case, the CD-DA decoder 120B outputs reproduced data to theCD-ROM decoder 122 which corresponds to the second-track information.The CD-ROM decoder 122 subjects the reproduced data to the CD-ROMdecoding process including the de-interleaving process. The CD-ROMdecoder 122 outputs the process-resultant data to the MPEG decoder 129.The MPEG decoder 129 subjects the output signal of the CD-ROM decoder122 to an MPEG decoding process. The MPEG decoder 129 outputs thedecoding-resultant data to the CPU 114A which corresponds to thesecond-track information. The step S120A receives the decoding-resultantdata from the MPEG decoder 129 which corresponds to the second-trackinformation.

A step S122A subsequent to the step S120A decides whether or not thedecoding-resultant data corresponding to the second-track information isnormal. When the decoding-resultant data is normal, the program advancesfrom the step S122A to a step S124A. Otherwise, the program advancesfrom the step S122 to the step S126.

The step S124A controls the switch 128A so that the movable contact ofthe switch 128A will connect with the fixed contact “j” thereof. In thiscase, the MPEG decoder 129 is connected to the output circuit 112.

A step S125A following the step S124A controls the CPU 117 so thatinformation will be reproduced from second and later tracks on theoptical disc 101. In this case, the CD-DA decoder 120B outputsreproduced data to the CD-ROM decoder 122. The CD-ROM decoder 122subjects the reproduced data to the CD-ROM decoding process includingthe de-interleaving process. The CD-ROM decoder 122 outputs theprocess-resultant data to the MPEG decoder 129. The MPEG decoder 129subjects the output signal of the CD-ROM decoder 122 to the MPEGdecoding process. The MPEG decoder 129 outputs the decoding-resultantdata to the output circuit 112. After the step S125A, the currentexecution cycle of the program segment ends.

It should be noted that the CD-ROM encoder 121 and the CD-ROM decoder122 may be replaced by a DVD encoder (a DVD packing encoder) and a DVDdecoder (a DVD unpacking decoder), respectively. In this case, the stepS117A in FIG. 18 is modified to refer to MPEG code words rather thanvideo-CD code words.

Seventh Embodiment

FIG. 19 shows a seventh embodiment of this invention which is similar tothe embodiment of FIG. 15 except for the following design changes. Theembodiment of FIG. 19 includes an orthogonal transform encoder 125Ainstead of the orthogonal transform/Huffman encoder 125 in FIG. 15. Theembodiment of FIG. 19 includes an orthogonal transform decoder 126Ainstead of the orthogonal transform/Huffman decoder 126 in FIG. 15.

The orthogonal transform encoder 125A implements only orthogonaltransform on received data. The orthogonal transform decoder 126Aimplements only inverse orthogonal transform on received data.

It should be noted that the CD-ROM encoder 121 and the CD-ROM decoder122 may be replaced by a DVD encoder (a DVD packing encoder) and a DVDdecoder (a DVD unpacking decoder), respectively.

Eighth Embodiment

FIG. 20 shows an eighth embodiment of this invention which is similar tothe embodiment of FIG. 17 except for the following design changes. Theembodiment of FIG. 20 includes an orthogonal transform encoder 125Ainstead of the orthogonal transform/Huffman encoder 125 in FIG. 17. Theembodiment of FIG. 20 includes an orthogonal transform decoder 126Ainstead of the orthogonal transform/Huffman decoder 126 in FIG. 17.

The orthogonal transform encoder 125A implements only orthogonaltransform on received data. The orthogonal transform decoder 126Aimplements only inverse orthogonal transform on received data.

It should be noted that the CD-ROM encoder 121 and the CD-ROM decoder122 may be replaced by a DVD encoder (a DVD packing encoder) and a DVDdecoder (a DVD unpacking decoder), respectively.

Ninth Embodiment

FIG. 21 shows a ninth embodiment of this invention which is similar tothe embodiment of FIG. 15 except for the following design changes. Theembodiment of FIG. 21 includes a Huffman encoder 125B instead of theorthogonal transform/Huffman encoder 125 in FIG. 15. The embodiment ofFIG. 21 includes a Huffman decoder 126B instead of the orthogonaltransform/Huffman decoder 126 in FIG. 15.

The Huffman encoder 125B implements only a Huffman encoding process onreceived data. The Huffman decoder 126B implements only a Huffmandecoding process on received data.

It should be noted that the CD-ROM encoder 121 and the CD-ROM decoder122 may be replaced by a DVD encoder (a DVD packing encoder) and a DVDdecoder (a DVD unpacking decoder), respectively.

Tenth Embodiment

FIG. 22 shows a tenth embodiment of this invention which is similar tothe embodiment of FIG. 17 except for the following design changes. Theembodiment of FIG. 22 includes a Huffman encoder 125B instead of theorthogonal transform/Huffman encoder 125 in FIG. 17. The embodiment ofFIG. 22 includes a Huffman decoder 126B instead of the orthogonaltransform/Huffman decoder 126 in FIG. 17.

The Huffman encoder 125B implements only a Huffman encoding process onreceived data. The Huffman decoder 126B implements only a Huffmandecoding process on received data.

The embodiment of FIG. 22 includes a switch 127A instead of the switch127 in FIG. 17. The embodiment of FIG. 22 includes a CPU 114B instead ofthe CPU 114A in FIG. 17. The embodiment of FIG. 22 includes an MPEGdecoder 130.

The switch 127A has a movable contact and fixed contacts “g”, “h”, and“k”. The switch 127A has a control terminal. The switch 127A ischangeable among four different states in response to a signal fed tothe control terminal. When the switch 127A assumes a first state, themovable contact thereof connects with the fixed contact “g” thereof anddisconnects from the fixed contacts “h” and “k” thereof. When the switch127A assumes a second state, the movable contact thereof connects withthe fixed contact “h” thereof and disconnects from the fixed contacts“g” and “k” thereof. When the switch 127A assumes a third state, themovable contact thereof connects with the fixed contact “k” thereof anddisconnects from the fixed contacts “g” and “h” thereof. When the switch127A assumes a fourth state, the movable contact thereof connects withnone of the fixed contacts “g”, “h”, and “k” thereof. The controlterminal of the switch 127A is connected to the CPU 114B. The fixedcontact “g” of the switch 127A leads to the movable contact of theswitch 123. The fixed contact “h” of the switch 127A leads to the inputside of the Huffman encoder 125B. The fixed contact “k” of the switch127A leads to the input side of the MPEG encoder 130. The movablecontact of the switch 127A leads from the output side of the inputcircuit 113B. The output side of the MPEG encoder 130 is connected tothe movable contact of the switch 123.

It is assumed that the user designates the recording mode of operationof the apparatus of FIG. 22 by actuating the operation unit 115. In thiscase, the user also designates the format by actuating the operationunit 115. Generally, the designated format corresponds to the standardsof an optical disc 101 set in the normal position within the apparatusof FIG. 22. The operation unit 115 informs the CPU 117 that therecording mode of operation is currently designated. Also, the operationunit 115 informs the CPU 117 of the currently designated format. The CPU117 transfers the information of the currently designated operation modeand the currently designated format to the CPU 114B. When the currentlydesignated format agrees with the video-CD format, the CPU 114B controlsthe switches 123 and 127A so that the movable contact of the switch 123connects with the fixed contact “f” thereof and the movable contact ofthe switch 127A connects with the fixed contact “k” thereof. Therefore,the MPEG encoder 130 is connected to the input circuit 113B while theHuffman encoder 125B is disconnected from the input circuit 113B. Inthis case, the digital signal is transmitted from the input circuit 113Bto the MPEG encoder 130. The MPEG encoder 130 subjects the digitalsignal to an MPEG encoding process to compress the digital signal. TheMPEG encoder 130 outputs the resultant digital signal to the CD-ROMencoder 121. The CD-ROM encoder 121 subjects the output signal of theMPEG encoder 130 to the CD-ROM encoding process including theinterleaving process. The CD-ROM encoder 121 outputs theprocess-resultant digital signal to the CD-DA encoder 120A. The CD-DAencoder 120A subjects the output signal of the CD-ROM encoder 121 to theCIRC encoding process. The CD-DA encoder 120A outputs theencoding-resultant digital signal to the recording encoder 110 asrecorded data (data to be recorded) of the video-CD format. Therecording encoder 110 subjects the recorded data of the video-CD formatto the EFM modulation. The recording encoder 110 outputs themodulation-resultant signal to the laser drive section 109. The opticalhead 103 applies the laser light beam to the optical disc 101. The laserdrive section 109 controls the power or the intensity of the laser lightbeam in response to the output signal of the recording encoder 110 sothat information corresponding to the recorded data of the video-CDformat is recorded on the optical disc 101. Furthermore, TOC informationrelated to the recorded data is generated, and the TOC information isrecorded on the inner area of the optical disc 101.

It should be noted that the CD-ROM encoder 121 and the CD-ROM decoder122 may be replaced by a DVD encoder (a DVD packing encoder) and a DVDdecoder (a DVD unpacking decoder), respectively.

Eleventh Embodiment

FIG. 23 shows an eleventh embodiment of this invention which is similarto the embodiment of FIG. 15 except for the following design changes.The embodiment of FIG. 23 includes a CPU 114D instead of the CPU 114 inFIG. 15. The CPU 114D is connected to the CD-DA encoder 120A. Theembodiment of FIG. 23 includes a compression encoder 125C, an expansiondecoder 126C, and switches 127B and 128B. The embodiment of FIG. 23 isable to handle an optical disc 101 which can be selected from amongvarious discs such as a CD-DA and a CD-ROM-audio.

The switch 127B has a movable contact and fixed contacts “g”, “h1”,“h2”, and “h3”. The switch 127B has a control terminal. The switch 127Bis changeable among five different states in response to a signal fed tothe control terminal. When the switch 127B assumes a first state, themovable contact thereof connects with the fixed contact “g” thereof anddisconnects from the fixed contacts “h1”, “h2”, and “h3” thereof. Whenthe switch 127B assumes a second state, the movable contact thereofconnects with the fixed contact “h1” thereof and disconnects from thefixed contacts “g”, “h2”, and “h3” thereof. When the switch 127B assumesa third state, the movable contact thereof connects with the fixedcontact “h2” thereof and disconnects from the fixed contacts “g”, “h1”,and “h3” thereof. When the switch 127B assumes a fourth state, themovable contact thereof connects with the fixed contact “h3” thereof anddisconnects from the fixed contacts “g”, “h1”, and “h2” thereof when theswitch 127B assumes a fifth state, the movable contact thereof connectswith none of the fixed contacts “g”, “h1”, “h2”, and “h3” thereof. Thecontrol terminal of the switch 127B is connected to the CPU 114D. Thefixed contact “g” of the switch 127B leads to the input side of theCD-ROM encoder 121. The fixed contact “h1” of the switch 127B leads to afirst input side of the compression encoder 125C. The fixed contact “h2”of the switch 127B leads to a second input side of the compressionencoder 125C. The fixed contact “h3” of the switch 127B leads to a thirdinput side of the compression encoder 125C. The movable contact of theswitch 127B leads from the output side of the input circuit 113. Theoutput side of the compression encoder 125C is connected to the inputside of the CD-ROM encoder 121.

The switch 128B has a movable contact and fixed contacts “c1”, “c2”,“c3”, and “d”. The switch 128B has a control terminal. The switch 128Bis changeable among five different states in response to a signal fed tothe control terminal. When the switch 128B assumes a first state, themovable contact thereof connects with the fixed contact “c1” thereof anddisconnects from the fixed contact “c2”, “c3”, and “d” thereof. When theswitch 128B assumes a second state, the movable contact thereof connectswith the fixed contact “c2” thereof and disconnects from the fixedcontacts “c1”, “c3”, and “d” thereof. When the switch 128B assumes athird state, the movable contact thereof connects with the fixed contact“c3” thereof and disconnects from the fixed contacts “c1”, “c2”, and “d”thereof. When the switch 128B assumes a fourth state, the movablecontact thereof connects with the fixed contact “d” thereof anddisconnects from the fixed contacts “c1”, “c2”, and “c3” thereof. Whenthe switch 128B assumes a fifth state, the movable contact thereofconnects with none of the fixed contacts “c1”, “c2”, “c3”, and “d”thereof. The control terminal of the switch 128B is connected to the CPU114D. The fixed contact “c1” of the switch 128B leads from a firstoutput side of the expansion decoder 126C. The fixed contact “c2” of theswitch 128B leads from a second output side of the expansion decoder126C. The fixed contact “c3” of the switch 128B leads from a thirdoutput side of the expansion decoder 126C. The fixed contact “d” of theswitch 128B leads from the output side of the CD-ROM decoder 122. Themovable contact of the switch 128B leads to the input side of the outputcircuit 112. In addition, the movable contact of the switch 128B isconnected to the CPU 114D. The input side of the compression decoder126C is connected to the output side of the CD-ROM decoder 122.

As shown in FIG. 24, the compression encoder 125C includes an orthogonaltransform encoder 125P, and Huffman encoders 125Q and 125R. The inputside of the orthogonal transform encoder 125P is connected to the fixedcontact “h1” of the switch 127B The output side of the orthogonaltransform encoder 125P is connected to the input side of the CD-ROMencoder 121. The input side of the Huffman encoder 125Q is connected tothe fixed contact “h2” of the switch 127B. The output side of theHuffman encoder 125Q is connected to the input side of the orthogonaltransform encoder 125P. The input side of the Huffman encoder 125R isconnected to the fixed contact “h3” of the switch 127B. The output sideof the Huffman encoder 125R is connected to the input side of the CD-ROMencoder 121.

As shown in FIG. 25, the expansion decoder 126C includes an orthogonaltransform decoder 126P, and Huffman decoders 126Q and 126R. The inputside of the orthogonal transform decoder 126P is connected to the outputside of the CD-ROM decoder 122. The output side of the orthogonaltransform decoder 126P is connected to the fixed contact “c1” of theswitch 128B. The input side of the Huffman decoder 126Q is connected tothe output side of the orthogonal transform decoder 126P. The outputside of the Huffman decoder 126Q is connected to the fixed contact “c2”of the switch 128B. The input side of the Huffman decoder 126R isconnected to the output side of the CD-ROM decoder 122. The output sideof the Huffman decoder 126R is connected to the fixed contact “c3” ofthe switch 128B.

The button in the operation unit 115 can also be used in selecting anddesignating one out of three different signal processing types, that is,first, second, and third processing types.

It is assumed that the user designates the recording mode of operationof the apparatus of FIG. 23 by actuating the operation unit 115. In thiscase, the user also designates the format and the processing type byactuating the operation unit 115. Generally, the designated formatcorresponds to the standards of an optical disc 101 set in the normalposition within the apparatus of FIG. 23. The operation unit 115 informsthe CPU 117 that the recording mode of operation is currentlydesignated. Also, the operation unit 115 informs the CPU 117 of thecurrently designated format and the currently designated processingtype. The CPU 117 transfers the information of the currently designatedoperation mode, the currently designated format, and the currentlydesignated processing type to the CPU 114D. When the currentlydesignated format agrees with the CD-ROM format, the CPU 114D controlsthe switch 127B so that the movable contact of the switch 127B connectswith the fixed contact “g” thereof. Therefore, the CD-ROM encoder 121 isconnected to the input circuit 113 while the compression encoder 125C isdisconnected from the input circuit 113. In this case, the output signalof the input circuit 113 travels the CD-ROM encoder 121 while bypassingthe compression encoder 125C. The CD-ROM encoder 121 subjects the outputsignal of the input circuit 113 to the CD-ROM encoding process includingthe interleaving process. The CD-ROM encoder 121 outputs theprocess-resultant digital signal to the CD-DA encoder 120A. The CD-DAencoder 120A subjects the output signal of the CD-ROM encoder 121 to theCIRC encoding process. The CD-DA encoder 120A outputs theencoding-resultant digital signal to the recording encoder 110 asrecorded data (data to be recorded) of the CD-ROM format. The recordingencoder 110 subjects the recorded data of the CD-ROM format to the EFMmodulation. The recording encoder 110 outputs the modulation-resultantsignal to the laser drive section 109. The optical head 103 applies thelaser light beam to the optical disc 101. The laser drive section 109controls the power or the intensity of the laser light beam in responseto the output signal of the recording encoder 110 so that informationcorresponding to the recorded data of the CD-ROM format is recorded onthe optical disc 101. Furthermore, TOC information related to therecorded data is generated, and the TOC information is recorded on theinner area of the optical disc 101.

A consideration will be given of the case where the user designates therecording mode of operation of the apparatus of FIG. 23 and alsodesignates the format and the processing type. When the designatedformat agrees with the CD-ROM-audio format and the designated processingtype agrees with the first processing type, the CPU 114D controls theswitch 127B so that the movable contact of the switch 127B connects withthe fixed contact “h1” thereof. Therefore, the output signal of theinput circuit 113 travels the compression encoder 125C via the fixedcontact “h1” of the switch 127B. In this case, the orthogonal transformencoder 125P in the compression encoder 125C subjects the output signalof the input circuit 113 to a data-compression encoding process usingorthogonal transform. The orthogonal transform encoder 125P in thecompression encoder 125C outputs the resultant signal to the CD-ROMencoder 121. The CD-ROM encoder 121 subjects the output signal of thecompression encoder 125C to the CD-ROM encoding process including theinterleaving process. The CD-ROM encoder 121 outputs theprocess-resultant digital signal to the CD-DA encoder 120A. The CD-DAencoder 120A subjects the output signal of the CD-ROM encoder 121 to theCIRC encoding process. The CD-DA encoder 120A outputs theencoding-resultant digital signal to the recording encoder 110 asrecorded data (data to be recorded) of the CD-ROM-audio format. Therecording encoder 110 subjects the recorded data of the CD-ROM-audioformat to the EFM modulation. The recording encoder 110 outputs themodulation-resultant signal to the laser drive section 109. The opticalhead 103 applies the laser light beam to the optical disc 101. The laserdrive section 109 controls the power or the intensity of the laser lightbeam in response to the output signal of the recording encoder 110 sothat information corresponding to the recorded data of the CD-ROM-audioformat is recorded on the optical disc 101. Furthermore, TOC informationrelated to the recorded data is generated, and the TOC information isrecorded on the inner area of the optical disc 101. The CPU 114Dcontrols the CD-DA encoder 120A so that an information piecerepresenting the use of the first processing type will be added to theTOC information.

A further consideration will be given of the case where the userdesignates the recording mode of operation of the apparatus of FIG. 23and also designates the format and the processing type. When thedesignated format agrees with the CD-ROM-audio format and the designatedprocessing type agrees with the second processing type, the CPU 114Dcontrols the switch 127B so that the movable contact of the switch 127Bconnects with the fixed contact “h2” thereof. Therefore, the outputsignal of the input circuit 113 travels the compression encoder 125C viathe fixed contact “h2” of the switch 127B. In this case, the Huffmanencoder 125Q in the compression encoder 125C subjects the output signalof the input circuit 113 to a Huffman encoding process. The Huffmanencoder 125Q outputs the resultant signal to the orthogonal transformencoder 125P in the compression encoder 125C. The orthogonal transformencoder 125P subjects the output signal of the Huffman encoder 125Q tothe data-compression encoding process using the orthogonal transform.The orthogonal transform encoder 125P in the compression encoder 125Coutputs the resultant signal to the CD-ROM encoder 121. The CD-ROMencoder 121 subjects the output signal of the compression encoder 125Cto the CD-ROM encoding process including the interleaving process. TheCD-ROM encoder 121 outputs the process-resultant digital signal to theCD-DA encoder 120A. The CD-DA encoder 120A subjects the output signal ofthe CD-ROM encoder 121 to the CIRC encoding process. The CD-DA encoder120A outputs the encoding-resultant digital signal to the recordingencoder 110 as recorded data (data to be recorded) of the CD-ROM-audioformat. The recording encoder 110 subjects the recorded data of theCD-ROM-audio format to the EFM modulation. The recording encoder 110outputs the modulation-resultant signal to the laser drive section 109.The optical head 103 applies the laser light beam to the optical disc101. The laser drive section 109 controls the power or the intensity ofthe laser light beam in response to the output signal of the recordingencoder 110 so that information corresponding to the recorded data ofthe CD-ROM-audio format is recorded on the optical disc 101.Furthermore, TOC information related to the recorded data is generated,and the TOC information is recorded on the inner area of the opticaldisc 101. The CPU 114D controls the CD-DA encoder 120A so that aninformation piece representing the use of the second processing typewill be added to the TOC information.

A still further consideration will be given of the case where the userdesignates the recording mode of operation of the apparatus of FIG. 23and also designates the format and the processing type. When thedesignated format agrees with the CD-ROM-audio format and the designatedprocessing type agrees with the third processing type, the CPU 114Dcontrols the switch 127B so that the movable contact of the switch 127Bconnects with the fixed contact “h3” thereof. Therefore, the outputsignal of the input circuit 113 travels the compression encoder 125C viathe fixed contact “h3” of the switch 127B. In this case, the Huffmanencoder 125R in the compression encoder 125C subjects the output signalof the input circuit 113 to a Huffman encoding process. The Huffmanencoder 125R in the compression encoder 125C outputs the resultantsignal to the CD-ROM encoder 121. The CD-ROM encoder 121 subjects theoutput signal of the compression encoder 125C to the CD-ROM encodingprocess including the interleaving process. The CD-ROM, encoder 121outputs the process-resultant digital signal to the CD-DA encoder 120A.The CD-DA encoder 120A subjects the output signal of the CD-ROM encoder121 to the CIRC encoding process. The CD-DA encoder 120A outputs theencoding-resultant digital signal to the recording encoder 110 asrecorded data (data to be recorded) of the CD-ROM-audio format. Therecording encoder 110 subjects the recorded data of the CD-ROM-audioformat to the EFM modulation. The recording encoder 110 outputs themodulation-resultant signal to the laser drive section 109. The opticalhead 103 applies the laser light beam to the optical disc 101. The laserdrive section 109 controls the power or the intensity of the laser lightbeam in response to the output signal of the recording encoder 110 sothat information corresponding to the recorded data of the CD-ROM-audioformat is recorded on the optical disc 101. Furthermore, TOC informationrelated to the recorded data is generated, and the TOC information isrecorded on the inner area of the optical disc 101. The CPU 114Dcontrols the CD-DA encoder 120A so that an information piecerepresenting the use of the third processing type will be added to theTOC information.

FIG. 26 is a flowchart of a segment of a program in the CPU 114D. Theprogram segment in FIG. 26 relates to the playback mode of operation ofthe apparatus of FIG. 23. As shown in FIG. 26, a first step S201 of theprogram segment reads out TOC information from the RAM within the CPU117.

A step S207 following the step S201 controls the CPU 117 so thatinformation will be reproduced from the first track on the optical disc101. The step S207 receives reproduced data from the CD-DA decoder 120Bwhich represents the first-track information.

A step S208 subsequent to the step S207 decides whether or not thefirst-track information has CD-ROM-audio code words. When thefirst-track information has CD-ROM-audio code words, the programadvances from the step S208 to a step S250. In this case, it is decidedthat the optical disc 101 agrees with a CD-ROM-audio. When thefirst-track information does not have any CD-ROM-audio code words, theprogram advances from the step S208 to a step S217.

The step S250 decides which of the first, second, and third processingtypes is used by referring to the TOC information. When the firstprocessing type is used, the program advances from the step S250 to astep S251A. When the second processing type is used, the programadvances from the step S250 to a step S251B. When the third processingtype is used, the program advances from the step S250 to a step S251C.

The step S251A controls the switch 128B so that the movable contact ofthe switch 128B will connect with the fixed contact “c1”. The step S251Bcontrols the switch 128B so that the movable contact of the switch 128Bwill connect with the fixed contact “c2”. The step S251C controls theswitch 128B so that the movable contact of the switch 128B will connectwith the fixed contact “c3”.

A step S252 following the steps S251A, S251B, and S251C controls the CPU117 so that information will be reproduced from second and later trackson the optical disc 101. In this case, the CD-DA decoder 120B outputsreproduced data to the CD-ROM decoder 122. The CD-ROM decoder 122subjects the reproduced data to the CD-ROM decoding process includingthe de-interleaving process. The CD-ROM decoder 122 outputs theprocess-resultant data to the expansion decoder 126C. The orthogonaltransform decoder 126P in the expansion decoder 126C subjects the outputsignal of the CD-ROM decoder 122 to a data-expansion decoding processusing inverse orthogonal transform. The orthogonal transform decoder126P in the expansion decoder 126C outputs the resultant signal to thefixed contact “c1” of the switch 128B and also the Huffman decoder 126Qin the expansion decoder 126C. The Huffman decoder 126Q in the expansiondecoder 126C subjects the output signal of the orthogonal transformdecoder 126P to a Huffman decoding process. The Huffman decoder 126Q inthe expansion decoder 126C outputs the resultant signal to the fixedcontact “c2” of the switch 128B. The Huffman decoder 126R in theexpansion decoder 126C subjects the output signal of the CD-ROM decoder122 to a Huffman decoding process. The Huffman decoder 126R in theexpansion decoder 126C outputs the resultant signal to the fixed contact“c3” of the switch 128B. When the movable contact of the switch 128Bconnects with the fixed contact “c1” thereof, the output signal of theorthogonal transform decoder 126P in the expansion decoder 126C travelsto the output circuit 112. When the movable contact of the switch 128Bconnects with the fixed contact “c2” thereof, the output signal of theHuffman decoder 126Q in the expansion decoder 126C travels to the outputcircuit 112. When the movable contact of the switch 128B connects withthe fixed contact “c3” thereof, the output signal of the Huffman decoder126R in the expansion decoder 126C travels to the output circuit 112.After the step S252, the current execution cycle of the program segmentends.

The step S217 decides whether or not the first-track information hasCD-ROM code words. When the first-track information has CD-ROM codewords, the program advances from the step S217 to a step S224. In thiscase, it is decided that the optical disc 101 agrees with a CD-ROM. Whenthe first-track information does not have any CD-ROM code words, theprogram advances from the step S217 to the step S226.

The step S224 controls the switch 128B so that the movable contact ofthe switch 128B will connect with the fixed contact “d” thereof. In thiscase, the CD-ROM decoder 122 is connected to the output circuit 112while the expansion decoder 126C is disconnected from the output circuit112.

A step S225 following the step S224 controls the CPU 117 so thatinformation will be reproduced from the first and later tracks on theoptical disc 101. In this case, the CD-DA decoder 120B outputsreproduced data to the CD-ROM decoder 122. The CD-ROM decoder 122subjects the reproduced data to the CD-ROM decoding process includingthe de-interleaving process. The CD-ROM decoder 122 outputs theprocess-resultant data to the output circuit 112. After the step S225,the current execution cycle of the program segment ends.

The step S226 controls the CPU 117 so that the CPU 117 will output agiven display signal to the display unit 116. The given display signalis indicated by the display unit 116. The given display signalrepresents that information can not be normally reproduced from theoptical disc 101. In other words, the given display signal represents afailure of the reproduction of information from the optical disc 101.After the step S226, the current execution cycle of the program segmentends.

It should be noted that the CD-ROM encoder 121 and the CD-ROM decoder122 may be replaced by a DVD encoder (a DVD packing encoder) and a DVDdecoder (a DVD unpacking decoder), respectively. In this case, the stepS217 in FIG. 26 is modified to refer to MPEG code words rather thanCD-ROM code words.

Twelfth Embodiment

FIG. 27 shows a twelfth embodiment of this invention which is similar tothe embodiment of FIG. 23 except for the following design changes. Theembodiment of FIG. 27 includes a CPU 114E instead of the CPU 114D inFIG. 23. The embodiment of FIG. 27 includes a switch 128D instead of theswitch 128B in FIG. 23. The embodiment of FIG. 27 includes an MPEGdecoder 129. The embodiment of FIG. 27 is able to handle an optical disc101 which can be selected from among various discs such as aCD-ROM-audio and a video-CD.

The switch 128D has a movable contact and fixed contacts “c1”, “c2”,“c3”, “d”, and “i”. The switch 128D has a control terminal. The switch128D is changeable among six different states in response to a signalfed to the control terminal. When the switch 128D assumes a first state,the movable contact thereof connects with only the fixed contact “c1”thereof. When the switch 128D assumes a second state, the movablecontact thereof connects with only the fixed contact “c2” thereof. Whenthe switch 128D assumes a third state, the movable contact thereofconnects with only the fixed contact “c3” thereof. When the switch 128Dassumes a fourth state, the movable contact thereof connects with onlythe fixed contact “d” thereof. When the switch 128D assumes a fifthstate, the movable contact thereof connects with only the fixed contact“i” thereof. When the switch 128B assumes a sixth states, the movablecontact thereof connects with none of the fixed contacts “c1”, “c2”,“c3”, “d”, and “i” thereof. The control terminal of the switch 128D isconnected to the CPU 114E. The fixed contact “c1” of the switch 128Dleads from the first output side of the expansion decoder F 126C. Thefixed contact “c2” of the switch 128D leads from the second output sideof the expansion decoder 126C. The fixed contact “c3” of the switch 128Dleads from the third output side of the expansion decoder 126C. Thefixed contact “d” of the switch 128D leads from the output side of theCD-ROM decoder 122. The fixed contact “i” of the switch 128D leads fromthe output side of the MPEG decoder 129. The movable contact of theswitch 128D leads to the input side of the output circuit 112. The inputside of the MPEG decoder 129 is connected to the output side of theCD-ROM decoder 122. The output side of the MPEG decoder 129 is connectedto the CPU 114E.

FIG. 28 is a flowchart of a segment of a program in the CPU 114E. Theprogram segment in FIG. 28 is similar to the program segment in FIG. 26except for the following design changes. With reference to FIG. 28, astep S217A which replaces the step S217 in FIG. 26 decides whether ornot the first-track information has video-CD code words. When thefirst-track information has video-CD code words, the program advancesfrom the step S217A to a step S220A. In this case, it is decided thatthe optical disc 101 agrees with a video-CD. When the first-trackinformation does not have any video-CD code words, the program advancesfrom the step S217A to the step S226.

The step S220A controls the CPU 117 so that information will be read outfrom a second track on the optical disc 101. In this case, the CD-DAdecoder 120B outputs reproduced data to the CD-ROM decoder 122 whichcorresponds to the second-track information. The CD-ROM decoder 122subjects the reproduced data to the CD-ROM decoding process includingthe de-interleaving process. The CD-ROM decoder 122 outputs theprocess-resultant data to the MPEG decoder 129. The MPEG decoder 129subjects the output signal of the CD-ROM decoder 122 to an MPEG decodingprocess. The MPEG decoder 129 outputs the decoding-resultant data to theCPU 114E which corresponds to the second-track information. The stepS220A receives the decoding-resultant data from the MPEG decoder 129which corresponds to the second-track information.

A step S222A subsequent to the step S220A decides whether or not thedecoding-resultant data corresponding to the second-track information isnormal. When the decoding-resultant data is normal, the program advancesfrom the step S222A to a step S224A. Otherwise, the program advancesfrom the step S222A to the step S226.

The step S224A controls the switch 128D so that the movable contact ofthe switch 128D will connect with the fixed contact “i” thereof. In thiscase, the MPEG decoder 129 is connected to the output circuit 112.

A step S225A following the step S224 controls the CPU 117 so thatinformation will be reproduced from second and later tracks on theoptical disc 101. In this case, the CD-DA decoder 120B outputsreproduced data to the CD-ROM decoder 122. The CD-ROM decoder 122subjects the reproduced data to the CD-ROM decoding process includingthe de-interleaving process. The CD-ROM decoder 122 outputs theprocess-resultant data to the MPEG decoder 129. The MPEG decoder 129subjects the output signal of the CD-ROM decoder 122 to the MPEGdecoding process. The MPEG decoder 129 outputs the decoding-resultantdata to the output circuit 112. After the step S225A, the currentexecution cycle of the program segment ends.

It should be noted that the CD-ROM encoder 121 and the CD-ROM decoder122 may be replaced by a DVD encoder (a DVD packing encoder) and a DVDdecoder (a DVD unpacking decoder), respectively. In this case, the stepS217A in FIG. 28 is modified to refer to MPEG code words rather thanvideo-CD code words.

1-17. (canceled) 18-21. (canceled)
 22. A signal reproducing methodcomprising the steps of: reproducing an encoding-resultant signal of apredetermined recording-medium format from a digital disc including aDVD, the encoding-resultant signal containing audio informationresulting from quantization of an audio signal including a multi-channelaudio signal including a 6-channel audio signal at a quantization degreehigher than a degree of quantization for a CD and at a quantizationsampling frequency higher than that for a CD, the quantization samplingfrequency including 48 kHz; decoding the reproduced encoding-resultantsignal into a formatting-resultant signal corresponding to apredetermined format for a digital disc including a DVD, theformatting-resultant signal including segments corresponding to userdata areas prescribed in the predetermined format, acompression-resultant signal being placed in the segments of theformatting-resultant signal; deformatting the formatting-resultantsignal into the compression-resultant signal; expanding thecompression-resultant signal into a quantization-resultant signal by aHuffman decoding process; and converting the quantization-resultantsignal into the audio signal including the multi-channel audio signal.23. A signal reproducing method comprising the steps of: reproducing anencoding-resultant signal of a predetermined recording-medium formatfrom a digital disc including a DVD, the encoding-resultant signalcontaining audio information resulting from quantization of an audiosignal including a multi-channel audio signal including a 6-channelaudio signal at a quantization degree higher than a degree ofquantization for a CD and at a quantization sampling frequencyquantization sampling frequency including 48 kHz; decoding thereproduced encoding-resultant signal into a formatting-resultant signalcorresponding to a predetermined format for a digital disc including aDVD, the formatting-resultant signal including segments corresponding touser data areas prescribed in the predetermined format, acompression-resultant signal being placed in the segments of theformatting-resultant signal; deformatting the formatting-resultantsignal into the compression-resultant signal; expanding thecompression-resultant signal into a quantization-resultant signal by oneof an orthogonal decoding process and a Huffman decoding process; andconverting the quantization-resultant signal into the audio signalincluding the multi-channel audio signal.
 24. A signal recording methodcomprising the steps of: quantizing an input audio signal including amulti-channel audio signal including a 6-channel audio signal into aquantization-resultant signal at a quantization degree higher than adegree of quantization for a CD and at a quantization sampling frequencyhigher than that for a CD, the quantization sampling frequency including48 kHz; compressing the quantization-resultant signal into acompression-resultant signal by a Huffman encoding process; formattingthe compression-resultant signal into a formatting-resultant signalcorresponding to a predetermined format for a digital disc including aDVD, the formatting-resultant signal including segments corresponding touser data areas prescribed in the predetermined format, thecompression-resultant signal being placed in the segments of theformatting-resultant signal; encoding the formatting-resultant signalinto an encoding-resultant signal of a predetermined recording-medium;and recording the encoding-resultant signal on a digital disc includinga DVD.
 25. A signal recording method as claimed in claim 24, wherein thecompressing step comprises: 1) dividing the quantization-resultantsignal into components corresponding to divided frequency bandsrespectively, and 2) compressing the components according tofrequency-band-dependent compression characteristics depending on apredetermined auditory sensation model.